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Cloudy pool water: what to check first

Doses checked 11/10/2026

First, look for the drain at the bottom of the deep end. If you can't see it, keep everyone out and ask a pool professional for a water test: the calculator gives no amounts for very cloudy water. If you can see it, test your water and enter the readings in the calculator below.

Your pool
Pool size

The volume of water in your pool. In UK gallons? UK gallons x 1.2 = US gallons.

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Same depth all over? Type it in both boxes.

Your test readings

Leave a box empty if you did not test it.

What you have

To raise a reading we use baking soda (sodium bicarbonate) for alkalinity, soda ash (sodium carbonate) for pH and cyanuric acid (stabilizer) for stabilizer, as the official charts list them.

Checked on every build: 283 tests of the sums this calculator runs, including 35 amounts printed in published charts, labels and manuals (ours must match them, or land under them where we start low on purpose) and 78 tests of its limits: caps, smaller rounds, and the cases where it gives no amount.

Can you see the drain?

CDC's pool inspection checklist includes the line Drain at the bottom of the deep end is visible. The Licking County Health Department (Ohio) guide gives Clarity Deepest point of pool visible from deck. If the drain at the bottom of the deep end is hidden, every chemical calculator on this site counts the water as very cloudy when you say so: no doses, keep everyone out, and ask a pool professional.

What your readings can show

If you can see the drain, the calculator above works through the readings in order. These are the ones it checks:

  • Free chlorine below its target, which goes up with stabilizer: it works out the chlorine to add.
  • Combined chlorine above 0.4 ppm: it tells you to use the shock calculator.
  • pH outside 7.4–7.6 or total alkalinity outside 80–120 ppm: it works out the amount, alkalinity first.
  • Calcium, stabilizer and salt, last.

What we don't cover

We don't list the causes of cloudy water. The official sources we use don't give a checked list of causes, so we'd be guessing. If your readings are in range and the water is still cloudy, ask a pool professional (for example a pool store water test).

Still cloudy after shocking

Retest combined chlorine once free chlorine is back at or below your label's level. If it is still above 0.4 ppm after a shock and a retest, ask a pool professional. If the water has turned very cloudy, keep everyone out.

Questions people ask

Why is my pool cloudy?

We don't list causes, because the official sources we use don't give a checked list. Check the drain first; if you can see it, test your water and use the calculator. If the readings are in range and it is still cloudy, ask a pool professional.

Can I swim in a cloudy pool?

If you can't see the drain at the bottom of the deep end, keep everyone out. Otherwise, go by your readings and your chlorine label's swimming level. This tool cannot tell you the water is safe to swim in. Follow your product label, and if in doubt ask a pool professional.

Why is my pool cloudy after shocking?

We can't tell you why. Keep everyone out until free chlorine is back at or below your label's level, then retest combined chlorine; if it is still above 0.4 ppm, or the water is very cloudy, ask a pool professional.

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The charts behind this page

Show all 69 figures and where each one comes from

Each figure this page and its calculator use. Open one for the source's own words, the other sources we checked it against, and the checks it has been through.

  • Minimum free chlorine, pool with no stabilizer (CYA): 1 ppm Official

    CDC Model Aquatic Health Code, 5th edition (2024), Code Official says: AQUATIC VENUES not using CYA shall maintain a minimum DPD-FC concentration of 1.0 ppm (mg/L). Source page (opens in a new browser tab)

    Also checked: CDC: Home pool and hot tub water treatment and testing Official says: CDC recommends pH 7.0–7.8 and a chlorine concentration of at least 1 ppm in pools and at least 3 ppm in hot tubs. Source page (opens in a new browser tab)

    Also checked: CDC healthy swimming infographic: inspection Official says: The free chlorine concentration should be at least 1 ppm in pools and at least 3 ppm in hot tubs/spas. Source page (opens in a new browser tab)

    Checked against the source on 11/9/2026. Re-opened by a second checker on 11/9/2026, who matched the source's words to this figure. Looked up again on 11/10/2026 by a checker who couldn't see our figure: it came back with the same figure.

  • Minimum free chlorine, pool with stabilizer (CYA) or stabilized chlorine: 2 ppm Official

    CDC Model Aquatic Health Code, 5th edition (2024), Code Official says: AQUATIC VENUES using CYA shall maintain a minimum DPDFC concentration of 2.0 ppm (mg/L). Source page (opens in a new browser tab)

    Also checked: CDC: Home pool and hot tub water treatment and testing Official says: If using cyanuric acid, a chlorine stabilizer, or chlorine products with cyanuric acid (for example, products commonly known as dichlor or trichlor [see product label]), CDC recommends pH 7.0–7.8 and a chlorine concentration of at least 2 ppm in pools. Source page (opens in a new browser tab)

    Also checked: Oregon Health Authority: Fact Sheet 6, Cyanuric Acid Official says: pools using CYA must maintain a minimum chlorine concentration of 2 ppm. Source page (opens in a new browser tab)

    Checked against the source on 11/9/2026. Re-opened by a second checker on 11/9/2026, who matched the source's words to this figure. Looked up again on 11/10/2026 by a checker who couldn't see our figure: it came back with the same figure.

  • Ideal free chlorine range (home pool target band): 2–4 ppm Official

    Licking County Health Department (Ohio): Pool and Spa Water Chemistry Adjustment Guide Official says: Free Chlorine (ppm) 1 2-4 N/A (recommended not higher than 5) Source page (opens in a new browser tab)

    Also checked: Oregon Health Authority: Water Quality Standards, OAR 333-062-1000 (public pools) Official says: Free Chlorine (w/CYA) 2.0ppm 2.0-4.0ppm 10.0ppm Source page (opens in a new browser tab)

    Also checked: Pentair IntelliChlor IC15/20/40/60 Installation and User's Guide, P/N 520589 Rev R Other source says: 2.0 - 4.0 ppm. Source page (opens in a new browser tab)

    Also checked: HTH 3" Chlorine Tabs Advanced product page Other source says: Add one tablet per 10,000 gallons of pool water every week, or as often as needed, to maintain a free available chlorine level of 1–4 ppm. Source page (opens in a new browser tab)

    Also checked: Hayward AquaRite Owner's Manual 092538 RevD Other source says: chlorine tests will show the desired 1-3ppm free chlorine reading. Source page (opens in a new browser tab)

    Also checked: Arkansas Department of Health Official says: Pool* 1.0 1.0 – 3.0 5.0 Source page (opens in a new browser tab)

    Also checked: Maryland Department of Health Official says: Free Chlorine 1.5 ppm 2.0 ppm – 3.0 ppm 10.0 ppm Source page (opens in a new browser tab)

    Checked against the source on 11/10/2026. Re-opened by a second checker on 11/9/2026, who matched the source's words to this figure.

  • Free chlorine above which chlorine labels say do not swim (re-entry level): 4 ppm Other source

    EPA-accepted label: B's Pool Supply Sodium Hypochlorite Solution 12.5% (EPA Reg. 55487-20001) Other source says: SWIMMING POOL WATER DISINFECTION – Do not reenter pool with a chlorine level above 4 ppm for risk of bodily harm. Source page (opens in a new browser tab)

    Also checked: EPA-accepted label: BioGuard Master Calcium Hypochlorite 67% (Bio-Lab, EPA Reg. 5185-238) Other source says: Reentry into treated swimming pool is prohibited above levels of 4 ppm chlorine due to risk of bodily injury. Source page (opens in a new browser tab)

    Also checked: EPA-accepted label: PDQ ChlorSan 8% Sodium Hypochlorite (EPA Reg. 58880-2) Other source says: Reentry into treated pools is prohibited above levels of 4.0 ppm due to risk of bodily harm. Source page (opens in a new browser tab)

    Also checked: HTH Pool Care Shock product page Other source says: Do not enter the pool until free available chlorine levels return to 1–4 ppm. Source page (opens in a new browser tab)

    Also checked: EPA-accepted label: Tarry trichlor 8 oz tablets/sticks (Qualco, EPA Reg. 3525-120) Other source says: Re-entry into treated swimming pools/spas is prohibited above levels of 3.0 ppm. Source page (opens in a new browser tab)

    Also checked: EPA-accepted label: Tarry trichlor 8 oz tablets/sticks (Qualco, EPA Reg. 3525-120) Other source says: Do not enter pool until the chlorine residual drops to 2.0 ppm (parts per million). Source page (opens in a new browser tab)

    Also checked: CDC Model Aquatic Health Code, 5th edition (2024), Code Official says: Maximum DPD-FC concentrations shall not exceed limits specified on the product label. Source page (opens in a new browser tab)

    Checked against the source on 11/9/2026. Re-opened by a second checker on 11/9/2026, who matched the source's words to this figure. Looked up again on 11/10/2026 by a checker who couldn't see our figure: it came back with the same figure.

  • Free chlorine reading above which the test may bleach out (false low): 10 ppm Official

    CDC: Home pool and hot tub water treatment and testing Official says: If the chlorine concentration of the water sampled from the pool or hot tub is more than 10 ppm, the test might partially or totally bleach out, resulting in a false low or 0 ppm chlorine result. Source page (opens in a new browser tab)

    Checked against the source on 11/9/2026. Re-opened by a second checker on 11/9/2026, who matched the source's words to this figure.

  • Free chlorine to keep, as a share of stabilizer (CYA): 7.5% of CYA Other source

    Orenda Technologies: What is the ideal CYA level for a swimming pool? Other source says: You could go higher, but you would also need to proportionally increase your free chlorine levels ... to maintain 7.5% of your CYA level in free chlorine. Source page (opens in a new browser tab)

    Also checked: AQUA Magazine Other source says: The free chlorine level should be 7.5 percent of CYA. Source page (opens in a new browser tab)

    Also checked: AQUA Magazine Other source says: As an example, you add 30 ppm of CYA and you will always need about 2 ppm of free chlorine (30 ppm × .075 = 2.25 ppm). Source page (opens in a new browser tab)

    Also checked: AQUA Magazine Other source says: Or if you have 50 ppm of CYA, you will need about 4 ppm of free chlorine (50 × .075 = 3.75 ppm). Source page (opens in a new browser tab)

    Also checked: Trouble Free Pool forum thread 'Chlorine/CYA chart vs 7.5% of CYA' Other source says: 7.5% is essentially the FC level where chlorine kills algae faster than it can reproduce Source page (opens in a new browser tab)

    Also checked: Oregon Health Authority: Fact Sheet 6, Cyanuric Acid Official says: Exceeding the CYA to free chlorine ratio of 45:1 means the chlorine is unable to kill pathogens in the water. Source page (opens in a new browser tab)

    Checked against the source on 11/9/2026. Re-opened by a second checker on 11/9/2026, who matched the source's words to this figure.

  • Combined chlorine level that calls for action (shock / superchlorinate): 0.4 ppm Official

    CDC Model Aquatic Health Code, 5th edition (2024), Code Official says: reduce the concentration of COMBINED CHLORINE (chloramines) in the water when the concentration exceeds 0.4 ppm (mg/L). Source page (opens in a new browser tab)

    Also checked: Oregon Health Authority: Water Quality Standards, OAR 333-062-1000 (public pools) Official says: Combined Chlorine 0ppm 0ppm 0.4ppm Source page (opens in a new browser tab)

    Also checked: Multnomah County (Oregon) Environmental Health: Water Treatment - Swimming Pools, EHS-0058 Official says: Breakpoint chlorinate when combined chlorine exceeds 0.5 ppm, or when chloramines are first detected. Source page (opens in a new browser tab)

    Checked against the source on 11/9/2026. Re-opened by a second checker on 11/9/2026, who matched the source's words to this figure. Looked up again on 11/10/2026 by a checker who couldn't see our figure: it came back with the same figure.

  • Ideal pH (calculator target band): 7.4–7.6 pH Official

    Licking County Health Department (Ohio): Pool and Spa Water Chemistry Adjustment Guide Official says: pH 7.2 7.4-7.6 7.8 Source page (opens in a new browser tab)

    Also checked: Multnomah County (Oregon) Environmental Health: Water Treatment - Swimming Pools, EHS-0058 Official says: Desirable range for pH in pools is 7.2 - 7.6. Source page (opens in a new browser tab)

    Also checked: EPA-accepted label: Tarry trichlor 8 oz tablets/sticks (Qualco, EPA Reg. 3525-120) Other source says: Maintain a pH level of 7.2 to 7.6 for best results. Source page (opens in a new browser tab)

    Also checked: Oregon Health Authority: Water Quality Standards, OAR 333-062-1000 (public pools) Official says: pH 7.0 7.2-7.6 7.8 Source page (opens in a new browser tab)

    Checked against the source on 11/9/2026. Re-opened by a second checker on 11/9/2026, who matched the source's words to this figure. Looked up again on 11/10/2026 by a checker who couldn't see our figure: it came back with the same figure.

  • pH range a standard phenol red test reads: 6.8–8.2 pH Other source

    Taylor Technologies: Midget Comparator, pH, Phenol Red, 6.8-8.2 Other source says: Midget Comparator, pH, Phenol Red, 6.8-8.2 Source page (opens in a new browser tab)

    Checked against the source on 11/9/2026. Re-opened by a second checker on 11/9/2026, who matched the source's words to this figure.

  • Acceptable total alkalinity range: 60–180 ppm Official

    CDC Model Aquatic Health Code, 5th edition (2024), Code Official says: Total alkalinity shall be maintained in the range of 60 to 180 ppm (mg/L). Source page (opens in a new browser tab)

    Also checked: AQUA Magazine Other source says: Total Alkalinity shall be maintained between a minimum of 60 and a maximum of 180 ppm. Source page (opens in a new browser tab)

    Also checked: Oregon Health Authority: Water Quality Standards, OAR 333-062-1000 (public pools) Official says: Total Alkalinity 60ppm 60-180ppm 180ppm Source page (opens in a new browser tab)

    Checked against the source on 11/9/2026. Re-opened by a second checker on 11/9/2026, who matched the source's words to this figure. Looked up again on 11/10/2026 by a checker who couldn't see our figure: it came back with the same figure.

  • Ideal total alkalinity (calculator target band): 80–120 ppm Official

    Licking County Health Department (Ohio): Pool and Spa Water Chemistry Adjustment Guide Official says: Total Alkalinity (ppm) 60 80-120 Should not impair ability to meet other Source page (opens in a new browser tab)

    Also checked: Pentair IntelliChlor IC15/20/40/60 Installation and User's Guide, P/N 520589 Rev R Other source says: 80 - 120 ppm Source page (opens in a new browser tab)

    Also checked: Leslie's: Alkalinity Up Other source says: The ideal ranges for any swimming pool should be between 80 and 120 ppm for Total Alkalinity. Source page (opens in a new browser tab)

    Also checked: Multnomah County (Oregon) Environmental Health: Water Treatment - Swimming Pools, EHS-0058 Official says: The desirable range for pools is 80-150 ppm Source page (opens in a new browser tab)

    Also checked: Alliance Trading 'pH DOWN' label, sodium bisulfate 93.2% Other source says: Balance total alkalinity in pool water to 80-125 ppm for plaster finishes and 125-150 for vinyl, fiberglass and other non-masonry finishes. Source page (opens in a new browser tab)

    Checked against the source on 11/9/2026. Re-opened by a second checker on 11/9/2026, who matched the source's words to this figure. Looked up again on 11/10/2026 by a checker who couldn't see our figure: it came back with the same figure.

  • Acceptable calcium hardness range (pools): 150–1,000 ppm Other source

    AQUA Magazine Other source says: Pool water calcium hardness shall be maintained between a minimum of 150 and a maximum of 1,000 ppm as CaCO3. Source page (opens in a new browser tab)

    Also checked: Oregon Health Authority: Water Quality Standards, OAR 333-062-1000 (public pools) Official says: Calcium Hardness 200ppm 200-400ppm 2500ppm Source page (opens in a new browser tab)

    Checked against the source on 11/9/2026. Re-opened by a second checker on 11/9/2026, who matched the source's words to this figure.

  • Ideal calcium hardness, plaster or concrete pool: 200–400 ppm Official

    Multnomah County (Oregon) Environmental Health: Water Treatment - Swimming Pools, EHS-0058 Official says: The desirable range for a plaster pool is 200-400 ppm. Source page (opens in a new browser tab)

    Also checked: Oregon Health Authority: Water Quality Standards, OAR 333-062-1000 (public pools) Official says: Calcium Hardness 200ppm 200-400ppm 2500ppm Source page (opens in a new browser tab)

    Also checked: Pentair IntelliChlor IC15/20/40/60 Installation and User's Guide, P/N 520589 Rev R Other source says: 200 - 400 ppm Source page (opens in a new browser tab)

    Also checked: Leslie's: Hardness Plus Other source says: The ideal range for calcium hardness in pool water is 200 to 400 ppm, Source page (opens in a new browser tab)

    Checked against the source on 11/9/2026. Re-opened by a second checker on 11/9/2026, who matched the source's words to this figure. Looked up again on 11/10/2026 by a checker who couldn't see our figure: it came back with the same figure.

  • Ideal calcium hardness, vinyl, painted or fiberglass pool: 175–300 ppm Official

    Multnomah County (Oregon) Environmental Health: Water Treatment - Swimming Pools, EHS-0058 Official says: For a vinyl, painted, or fiberglass pool, 175 -300 ppm. Source page (opens in a new browser tab)

    Checked against the source on 11/9/2026. Re-opened by a second checker on 11/9/2026, who matched the source's words to this figure.

  • Ideal stabilizer (cyanuric acid, CYA): 30–50 ppm Official

    Oregon Health Authority: Fact Sheet 6, Cyanuric Acid Official says: The ideal range for CYA is typically between 30-50 ppm. Source page (opens in a new browser tab)

    Also checked: Licking County Health Department (Ohio): Pool and Spa Water Chemistry Adjustment Guide Official says: Cyanuric Acid (ppm) 0 30-50 70 Source page (opens in a new browser tab)

    Also checked: Orenda Technologies: What is the ideal CYA level for a swimming pool? Other source says: We recommend 30-50 ppm CYA for residential pools. Source page (opens in a new browser tab)

    Also checked: the PHTA pool industry committee Other source says: A certain amount of cyanuric acid (usually within the range of 30 – 50 ppm) is necessary to protect outdoor pools from degradation by sunlight. Source page (opens in a new browser tab)

    Also checked: Pentair IntelliChlor IC15/20/40/60 Installation and User's Guide, P/N 520589 Rev R Other source says: 30 - 50 ppm Source page (opens in a new browser tab)

    Also checked: Arkansas Department of Health Official says: Add CYA separately, only as needed, to maintain 25–40 ppm in outdoor pools. Source page (opens in a new browser tab)

    Also checked: Arkansas Department of Health Official says: Anything above 50ppm CYA is considered high and can interfere with other pool chemicals' effects and equipment. Source page (opens in a new browser tab)

    Also checked: Maryland Department of Health Official says: Cyanuric Acid (if used) 30 ppm 40 ppm- 50 ppm 100 ppm Source page (opens in a new browser tab)

    Checked against the source on 11/10/2026. Re-opened by a second checker on 11/9/2026, who matched the source's words to this figure.

  • Stabilizer (CYA) level above which the tool says 'ask a pool professional': 70 ppm Official

    Licking County Health Department (Ohio): Pool and Spa Water Chemistry Adjustment Guide Official says: Cyanuric Acid (ppm) 0 30-50 70 Source page (opens in a new browser tab)

    Also checked: CDC Model Aquatic Health Code, 5th edition (2024), Code Official says: The CYA concentration at all AQUATIC VENUES shall remain at or below 90 ppm (mg/L). Source page (opens in a new browser tab)

    Also checked: Oregon Health Authority: Fact Sheet 6, Cyanuric Acid Official says: The CYA level at all AQUATIC VENUES shall remain at or below 90 ppm (mg/L). Source page (opens in a new browser tab)

    Also checked: the PHTA pool industry committee Other source says: If the cyanuric acid level exceeds the APSP maximum of 100 ppm, a partial drain and refi ll is recommended. Source page (opens in a new browser tab)

    Also checked: Arkansas Department of Health Official says: The MAHC & ADH recommend that CYA not exceed 90 ppm for standard pools. Source page (opens in a new browser tab)

    Also checked: Maryland Department of Health Official says: Cyanuric Acid (if used) 30 ppm 40 ppm- 50 ppm 100 ppm Source page (opens in a new browser tab)

    Checked against the source on 11/10/2026. Re-opened by a second checker on 11/9/2026, who matched the source's words to this figure.

  • Salt level for Hayward AquaRite salt chlorine generators: 2,700–3,400 (best 3,200) ppm Other source

    Hayward AquaRite Owner's Manual 092538 RevD Other source says: The ideal salt level is between 2700-3400 ppm (parts per million) with 3200 ppm being optimal. Source page (opens in a new browser tab)

    Checked against the source on 11/9/2026. Re-opened by a second checker on 11/9/2026, who matched the source's words to this figure.

  • Salt level for Pentair IntelliChlor salt chlorine generators: 3,600–4,500 (best 3,600) ppm Other source

    Pentair IntelliChlor IC15/20/40/60 Installation and User's Guide, P/N 520589 Rev R Other source says: 3600 - 4500 ppm (ideal 3600 ppm) Source page (opens in a new browser tab)

    Checked against the source on 11/9/2026. Re-opened by a second checker on 11/9/2026, who matched the source's words to this figure.

  • Default salt target in the calculator (user can change it to their generator's figure): 3,200 ppm Other source

    Hayward AquaRite Owner's Manual 092538 RevD Other source says: The ideal salt level is between 2700-3400 ppm (parts per million) with 3200 ppm being optimal. Source page (opens in a new browser tab)

    Also checked: Pentair IntelliChlor IC15/20/40/60 Installation and User's Guide, P/N 520589 Rev R Other source says: 3600 - 4500 ppm (ideal 3600 ppm) Source page (opens in a new browser tab)

    Checked against the source on 11/9/2026. Re-opened by a second checker on 11/9/2026, who matched the source's words to this figure.

  • Liquid chlorine (sodium hypochlorite solution): specific gravity (weight of 1 mL in grams) used to turn the label's % by weight into an amount by volume: 1.2 specific gravity (g per mL) Other source (worked out)

    Worked out: 1.195 rounded up to 1.2

    Alliance Chemical (Taylor, Texas): Safety Data Sheet, Sodium Hypochlorite 12.5% Other source says: Relative Density 1.195 at 20/20 °C (water = 1) Source page (opens in a new browser tab)

    Also checked: Alliance Chemical (Taylor, Texas): Safety Data Sheet, Sodium Hypochlorite 12.5% Other source says: Density 1.1929 g/cm³ at 20 °C Source page (opens in a new browser tab)

    Also checked: FPC (fpcusa.com): 10.0% Sodium Hypochlorite product sheet Other source says: Specific Gravity 1.13-1.20 @ 68F/20C Source page (opens in a new browser tab)

    Checked against the source on 11/9/2026.

  • Liquid chlorine: US fl oz to raise free chlorine 1 ppm in 10,000 US gal = 128 / (strength % x 1.2): 128/(strength x 1.2) Other source (worked out)

    Worked out: 1 ppm in 10,000 US gal = 37.85 g of available chlorine (10,000 × 3.785412 L × 1 mg per L, NIST). The label % is by weight (B's label: 12.5% sodium hypochlorite, 'Total available chlorine is 11.9%'), and the liquid weighs about 1.2 g per mL. So 1 mL holds at most strength/100 × 1.2 g of chlorine, and US fl oz per ppm = (3,785.412 ÷ 29.57353) ÷ (strength × 1.2) = 128 ÷ (strength × 1.2). Treating the whole label % as available chlorine (the label shows it is a little lower) keeps the amount on the low side.

    EPA-accepted label: B's Pool Supply Sodium Hypochlorite Solution 12.5% (EPA Reg. 55487-20001) Other source says: Total available chlorine is 11.9% Source page (opens in a new browser tab)

    Also checked: EPA-accepted label: B's Pool Supply Sodium Hypochlorite Solution 12.5% (EPA Reg. 55487-20001) Other source says: ACTIVE INGREDIENT: SODIUM HYPOCHLORITE………….. 12.5% Source page (opens in a new browser tab)

    Also checked: Alliance Chemical (Taylor, Texas): Safety Data Sheet, Sodium Hypochlorite 12.5% Other source says: Concentration 12.5% w/w Source page (opens in a new browser tab)

    Also checked: FPC (fpcusa.com): 10.0% Sodium Hypochlorite product sheet Other source says: Available Cl2 9.5-10.5 wt% ASTM D2022 Source page (opens in a new browser tab)

    Also checked: Alliance Chemical (Taylor, Texas): Safety Data Sheet, Sodium Hypochlorite 12.5% Other source says: Relative Density 1.195 at 20/20 °C (water = 1) Source page (opens in a new browser tab)

    Also checked: Indiana Department of Health: Adjusting Chemical Levels in a Swimming Pool / Water Chemistry Adjustment Guide Official says: Sodium Hypochlorite (12%) 10.7 fl.oz. 1.7 qts 3.3 qts Source page (opens in a new browser tab)

    Also checked: HASA liquid chlorine page Other source says: 12.5 PPM of free chlorine in 10,000 gallons—delivered by a single gallon of HASA’s 12.5% liquid chlorine Source page (opens in a new browser tab)

    Also checked: EPA-accepted label: PDQ ChlorSan 8% Sodium Hypochlorite (EPA Reg. 58880-2) Other source says: 80 to 160 oz. of product for each 10,000 gallons of water Source page (opens in a new browser tab)

    Also checked: EPA-accepted label: B's Pool Supply Sodium Hypochlorite Solution 12.5% (EPA Reg. 55487-20001) Other source says: For a new pool or when opening the pool in the spring, super chlorinate with 52 to 104 fl. oz. of product Source page (opens in a new browser tab)

    Also checked: Salt Lake County Health Department (Utah): pool chemical dosages Official says: Sodium Hypochlorite - Bleach 13 fl. oz. ½ gallon 1 gallon Source page (opens in a new browser tab)

    Also checked: Multnomah County (Oregon) Environmental Health: Water Treatment - Swimming Pools, EHS-0058 Official says: LIQUID 10% 1pt. 1ppm Source page (opens in a new browser tab)

    Checked against the source on 11/9/2026.

  • Dry chlorine: oz to raise free chlorine 1 ppm in 10,000 US gal = 1.3 / (strength % / 100): 1.3 oz of 100% available chlorine per ppm per 10,000 US gal Official

    Indiana Department of Health: Adjusting Chemical Levels in a Swimming Pool / Water Chemistry Adjustment Guide Official says: 1.0 ppm equals about .083 lbs of chemical per 10,000 gallons of water* or 1.3 oz per 10,000 gallons**. Source page (opens in a new browser tab)

    Also checked: Indiana Department of Health: Adjusting Chemical Levels in a Swimming Pool / Water Chemistry Adjustment Guide Official says: Calcium Hypochlorite (67%)* 2 oz 10 oz 1.3 lb Source page (opens in a new browser tab)

    Also checked: Indiana Department of Health: Adjusting Chemical Levels in a Swimming Pool / Water Chemistry Adjustment Guide Official says: Dichlor (56%) 2.4 oz 12 oz 1.4 lbs Source page (opens in a new browser tab)

    Also checked: Indiana Department of Health: Adjusting Chemical Levels in a Swimming Pool / Water Chemistry Adjustment Guide Official says: Dichlor (62%) 2.1 oz 10.75 oz 1.3 lbs Source page (opens in a new browser tab)

    Also checked: Indiana Department of Health: Adjusting Chemical Levels in a Swimming Pool / Water Chemistry Adjustment Guide Official says: Trichlor 1.5 oz 7.5 oz 14 oz Source page (opens in a new browser tab)

    Checked against the source on 11/9/2026. Re-opened by a second checker on 11/9/2026, who matched the source's words to this figure. Looked up again on 11/10/2026 by a checker who couldn't see our figure: it came back with the same figure.

  • 3-inch trichlor tablets: US gallons treated per tablet per week (label rate): 10,000 US gallons per tablet per week Other source

    HTH 3" Chlorine Tabs Advanced product page Other source says: Add one tablet per 10,000 gallons of pool water every week, or as often as needed, to maintain a free available chlorine level of 1–4 ppm. Source page (opens in a new browser tab)

    Also checked: EPA-accepted label: Tarry trichlor 8 oz tablets/sticks (Qualco, EPA Reg. 3525-120) Other source says: Suggested dosage is one {tablet}{stick} per 11,500 gallons of pool water per week. Source page (opens in a new browser tab)

    Checked against the source on 11/9/2026. Re-opened by a second checker on 11/9/2026, who matched the source's words to this figure.

  • Stabilizer (CYA) added by trichlor for each 1 ppm of chlorine: 0.6 ppm CYA per ppm FC Other source

    the PHTA pool industry committee Other source says: When trichlor is used, 0.6 ppm of cyanuric acid is added to the water for each ppm of available chlorine added. Source page (opens in a new browser tab)

    Also checked: Trouble Free Pool forum 'Compiled info on chemicals' (first-year owner) Other source says: It will add .6 part CYA for every 1 part of chlorine it adds. Source page (opens in a new browser tab)

    Checked against the source on 11/9/2026. Re-opened by a second checker on 11/9/2026, who matched the source's words to this figure.

  • Stabilizer (CYA) added by dichlor for each 1 ppm of chlorine: 1 ppm CYA per ppm FC Official (worked out)

    Worked out: Yakima: 1.6 lb = 25.6 oz raises stabilizer 10 ppm; at 2.5 oz per ppm, 25.6 oz raises chlorine 10.24 ppm; 10 ÷ 10.24 = 0.98. Salt Lake: 26 oz raises stabilizer 10 ppm; at 25 oz per 10 ppm, 26 oz raises chlorine 10.4 ppm; 10 ÷ 10.4 = 0.96. Rounded up to 1.0.

    Yakima County (Washington): Chemical Dosing chart Official says: Dichlor 1.6 pounds Source page (opens in a new browser tab)

    Also checked: Yakima County (Washington): Chemical Dosing chart Official says: Dichlor 2.5 ounces Source page (opens in a new browser tab)

    Also checked: Salt Lake County Health Department (Utah): pool chemical dosages Official says: Dichlor 13 oz. 26 oz. Not recommended Source page (opens in a new browser tab)

    Also checked: Trouble Free Pool forum 'Compiled info on chemicals' (first-year owner) Other source says: It will add .9 parts CYA for every 1 part chlorine it adds. Source page (opens in a new browser tab)

    Checked against the source on 11/9/2026.

  • Baking soda (sodium bicarbonate): lb to raise total alkalinity 10 ppm in 10,000 US gal: 1.4 lb per 10 ppm per 10,000 US gal Official

    Indiana Department of Health: Adjusting Chemical Levels in a Swimming Pool / Water Chemistry Adjustment Guide Official says: Sodium Bicarbonate 1.4 lbs 4.2 lbs 7.0 lbs Source page (opens in a new browser tab)

    Also checked: Salt Lake County Health Department (Utah): pool chemical dosages Official says: Sodium Bicarbonate 1 ½ lb. 7 ½ lb. 15 lb. Source page (opens in a new browser tab)

    Also checked: Yakima County (Washington): Chemical Dosing chart Official says: Sodium Bicarbonate (Baking Soda) 1.5 pounds Source page (opens in a new browser tab)

    Also checked: Multnomah County (Oregon) Environmental Health: Water Treatment - Swimming Pools, EHS-0058 Official says: For each 10,000 gallons of water, add 1.5 lbs. of sodium bicarbonate to raise the alkalinity 10 ppm. Source page (opens in a new browser tab)

    Also checked: Leslie's: Alkalinity Up Other source says: Dosage: 1-1/2 lb per 10,000 gallons increases alkalinity level by approximately 10 ppm Source page (opens in a new browser tab)

    Checked against the source on 11/9/2026. Re-opened by a second checker on 11/9/2026, who matched the source's words to this figure. Looked up again on 11/10/2026 by a checker who couldn't see our figure: it came back with the same figure.

  • Soda ash (sodium carbonate): oz to raise pH 0.2 in 10,000 US gal: 6 oz per 0.2 pH per 10,000 US gal Official

    Licking County Health Department (Ohio): Pool and Spa Water Chemistry Adjustment Guide Official says: Sodium Carbonate (Soda Ash) 6 oz. Source page (opens in a new browser tab)

    Also checked: Yakima County (Washington): Chemical Dosing chart Official says: Sodium Carbonate (Soda Ash) 6 ounces Source page (opens in a new browser tab)

    Checked against the source on 11/9/2026. Re-opened by a second checker on 11/9/2026, who matched the source's words to this figure. Looked up again on 11/10/2026 by a checker who couldn't see our figure: it came back with the same figure.

  • Soda ash side effect: total alkalinity rise per 0.2 pH step (6 oz per 10,000 US gal): 5 ppm TA Official

    Yakima County (Washington): Chemical Dosing chart Official says: (also raises total alkalinity 5ppm) Source page (opens in a new browser tab)

    Also checked: Indiana Department of Health: Adjusting Chemical Levels in a Swimming Pool / Water Chemistry Adjustment Guide Official says: Sodium Carbonate 14 oz 2.6 lbs 4.4 lbs Source page (opens in a new browser tab)

    Checked against the source on 11/9/2026. Re-opened by a second checker on 11/9/2026, who matched the source's words to this figure.

  • Muriatic acid (31.45%): US fl oz to lower pH 0.2 in 10,000 US gal: 12 US fl oz per 0.2 pH per 10,000 US gal Official

    Licking County Health Department (Ohio): Pool and Spa Water Chemistry Adjustment Guide Official says: Muriatic Acid 12 oz Source page (opens in a new browser tab)

    Also checked: Yakima County (Washington): Chemical Dosing chart Official says: Muriatic Acid (35% Hydrochloric Acid) 12 fluid ounces Source page (opens in a new browser tab)

    Checked against the source on 11/9/2026. Re-opened by a second checker on 11/9/2026, who matched the source's words to this figure. Looked up again on 11/10/2026 by a checker who couldn't see our figure: it came back with the same figure.

  • Dry acid (sodium bisulfate): lb per 0.2 pH step in 10,000 US gal (worked out from the label's pH band chart): 0.75 lb per 0.2 pH per 10,000 US gal Other source (worked out)

    Worked out: the label's 7.7-8.0 band dose (3/4 lb per 10,000 US gal) used as one 0.2 pH step.

    Alliance Trading 'pH DOWN' label, sodium bisulfate 93.2% Other source says: 7.7-8.0 3/4 lb. Source page (opens in a new browser tab)

    Also checked: Alliance Trading 'pH DOWN' label, sodium bisulfate 93.2% Other source says: 8.1-8.4 1-1/4 lbs. Source page (opens in a new browser tab)

    Also checked: Alliance Trading 'pH DOWN' label, sodium bisulfate 93.2% Other source says: Above 8.4 1-1/2 lbs. Source page (opens in a new browser tab)

    Also checked: Yakima County (Washington): Chemical Dosing chart Official says: Sodium Bisulfate (Dry Acid) 1.0 pound Source page (opens in a new browser tab)

    Also checked: Leslie's: Dry Acid pH Down Other source says: If the pH level is in the 7.6 - 7.8 range, add 15 oz. (about 2 cups) per 10,000 gallons of water. Source page (opens in a new browser tab)

    Checked against the source on 11/9/2026.

  • Dry acid side effect: total alkalinity drop for 1 lb in 10,000 US gallons: 5 ppm TA Official

    This is the chart's note for its 1 lb amount. The calculator's round of 0.75 lb is smaller, so it lowers alkalinity by less.

    Yakima County (Washington): Chemical Dosing chart Official says: (also lowers total alkalinity 5 ppm) Source page (opens in a new browser tab)

    Checked against the source on 11/9/2026. Re-opened by a second checker on 11/9/2026, who matched the source's words to this figure.

  • Muriatic acid (31.45%): US fl oz to lower total alkalinity 10 ppm in 10,000 US gal: 16 US fl oz per 10 ppm per 10,000 US gal Other source

    Leslie's: Muriatic Acid 2-Pack (28%-32%) Other source says: 2 cups of Muriatic Acid will lower Total Alkalinity by 10 ppm in 10,000 gallons of water. Source page (opens in a new browser tab)

    Also checked: Indiana Department of Health: Adjusting Chemical Levels in a Swimming Pool / Water Chemistry Adjustment Guide Official says: Muriatic Acid (31.4%) 26 fl.oz. 2.4 qts 1 gal Source page (opens in a new browser tab)

    Also checked: Licking County Health Department (Ohio): Pool and Spa Water Chemistry Adjustment Guide Official says: Muratic Acid (31.4%) 26 fl. oz. Source page (opens in a new browser tab)

    Also checked: Multnomah County (Oregon) Environmental Health: Water Treatment - Swimming Pools, EHS-0058 Official says: One quart of muriatic acid per 10,000 gallons of water will lower alkalinity by 12.5 ppm. Source page (opens in a new browser tab)

    Checked against the source on 11/10/2026. Re-opened by a second checker on 11/9/2026, who matched the source's words to this figure.

  • Dry acid: lb to lower total alkalinity 10 ppm in 10,000 US gal: 2 lb per 10 ppm per 10,000 US gal Other source

    Leslie's: Dry Acid pH Down Other source says: 2 lbs of Leslie's Dry Acid will decrease Total Alkalinity by 10 ppm in 10,000 gallons of water. Source page (opens in a new browser tab)

    Also checked: Indiana Department of Health: Adjusting Chemical Levels in a Swimming Pool / Water Chemistry Adjustment Guide Official says: Sodium Bisulfate 2.1 lbs 6.4 lbs 10.5 lbs Source page (opens in a new browser tab)

    Also checked: Multnomah County (Oregon) Environmental Health: Water Treatment - Swimming Pools, EHS-0058 Official says: Sodium bisulfate, added at a rate of 2.3 lbs. per 10,000 gallons of water, would lower the total alkalinity by 10 ppm. Source page (opens in a new browser tab)

    Checked against the source on 11/9/2026. Re-opened by a second checker on 11/9/2026, who matched the source's words to this figure.

  • Muriatic acid 14.5% (half-strength) dose: no published figure found Not confirmed

    We couldn't find a published figure for this. Follow your product's label, or ask a pool professional.

  • Calcium chloride 77%: lb to raise calcium hardness 10 ppm in 10,000 US gal: 1.2 lb per 10 ppm per 10,000 US gal Official

    Indiana Department of Health: Adjusting Chemical Levels in a Swimming Pool / Water Chemistry Adjustment Guide Official says: Calcium Chloride (77%) 1.2 lbs 3.6 lbs 6.0 lbs Source page (opens in a new browser tab)

    Also checked: Salt Lake County Health Department (Utah): pool chemical dosages Official says: Calcium Chloride 77% 1 ¼ lb. 6 ¼ lb. 12 ½ lb. Source page (opens in a new browser tab)

    Also checked: Yakima County (Washington): Chemical Dosing chart Official says: Calcium Chloride (77%) 1.25 pounds Source page (opens in a new browser tab)

    Also checked: Leslie's: Hardness Plus Other source says: Adding 1.25 pounds of hardness plus to 10,000 gallons of water will raise the calcium hardness by 10 ppm. Source page (opens in a new browser tab)

    Checked against the source on 11/9/2026. Re-opened by a second checker on 11/9/2026, who matched the source's words to this figure. Looked up again on 11/10/2026 by a checker who couldn't see our figure: it came back with the same figure.

  • Calcium chloride 100% (anhydrous): lb to raise calcium hardness 10 ppm in 10,000 US gal: 0.9 lb per 10 ppm per 10,000 US gal Official

    Indiana Department of Health: Adjusting Chemical Levels in a Swimming Pool / Water Chemistry Adjustment Guide Official says: Calcium Chloride (100%) 0.9 lbs 2.8 lbs 4.6 lbs Source page (opens in a new browser tab)

    Also checked: Salt Lake County Health Department (Utah): pool chemical dosages Official says: Calcium Chloride 100% 1 lb. 5 lb. 10 lb. Source page (opens in a new browser tab)

    Also checked: Yakima County (Washington): Chemical Dosing chart Official says: Calcium Chloride (100%) 1.0 pound Source page (opens in a new browser tab)

    Also checked: Multnomah County (Oregon) Environmental Health: Water Treatment - Swimming Pools, EHS-0058 Official says: For every 10,000 gallons of water, adding 1 pound of calcium chloride will increase calcium hardness 11 ppm. Source page (opens in a new browser tab)

    Checked against the source on 11/9/2026. Re-opened by a second checker on 11/9/2026, who matched the source's words to this figure.

  • Cyanuric acid (stabilizer, 100%): oz to raise CYA 10 ppm in 10,000 US gal: 13 oz per 10 ppm per 10,000 US gal Official

    Indiana Department of Health: Adjusting Chemical Levels in a Swimming Pool / Water Chemistry Adjustment Guide Official says: Cyanuric Acid*** 13 oz 2.5 lbs 4.1 lbs Source page (opens in a new browser tab)

    Also checked: Salt Lake County Health Department (Utah): pool chemical dosages Official says: Cyanuric Acid 6 ½ oz. 13 oz. 4 lb. Source page (opens in a new browser tab)

    Also checked: Yakima County (Washington): Chemical Dosing chart Official says: Cyanuric Acid (Conditioner) 13 ounces Source page (opens in a new browser tab)

    Also checked: Leslie's: Pool Stabilizer and Conditioner Other source says: Dosage: 2-1/2 lbs. per 10,000 gallons raises CYA level by 30 ppm Source page (opens in a new browser tab)

    Checked against the source on 11/9/2026. Re-opened by a second checker on 11/9/2026, who matched the source's words to this figure. Looked up again on 11/10/2026 by a checker who couldn't see our figure: it came back with the same figure.

  • Salt: lb to raise salt 1 ppm in 10,000 US gal: 0.083 lb per ppm per 10,000 US gal Official (worked out)

    Worked out: from Indiana's general rule for any 100% chemical (the guide does not name salt); Pentair's salt table agrees (0.0834).

    Indiana Department of Health: Adjusting Chemical Levels in a Swimming Pool / Water Chemistry Adjustment Guide Official says: 1.0 ppm equals about .083 lbs of chemical per 10,000 gallons of water* or 1.3 oz per 10,000 gallons**. Source page (opens in a new browser tab)

    Also checked: Pentair IntelliChlor IC15/20/40/60 Installation and User's Guide, P/N 520589 Rev R Other source says: Table 2 (10,000 US gal, target 3,600 ppm): current 0 -> 300.43 lb; 1,000 -> 216.98 lb; 2,000 -> 133.53 lb Source page (opens in a new browser tab)

    Checked against the source on 11/9/2026. Re-opened by a second checker on 11/9/2026, who matched the source's own words quoted here.

  • Most muriatic acid (31.45%) to add at one time: 13 US fl oz per 10,000 US gal per stage Other source (worked out)

    Worked out: Leslie's says Never add more than 16 oz per 10,000 gallons at one time. It doesn't say fluid or weight ounces. Read as weight, that is about 13 US fl oz, so the calculator uses 13 US fl oz per 10,000 US gal per stage.

    Leslie's: Muriatic Acid 2-Pack (28%-32%) Other source says: Never add more than 16 oz per 10,000 gallons at one time. Source page (opens in a new browser tab)

    Also checked: Indiana Department of Health: Adjusting Chemical Levels in a Swimming Pool / Water Chemistry Adjustment Guide Official says: Do not add more than one quart of acid per 10,000 gallons at one time. Source page (opens in a new browser tab)

    Checked against the source on 11/10/2026. Re-opened by a second checker on 11/9/2026, who matched the source's own words quoted here.

  • Most dry acid to add at one time: 1.5 lb per 10,000 US gal per stage Other source

    Alliance Trading 'pH DOWN' label, sodium bisulfate 93.2% Other source says: Never add more than 1.5 pounds of this product per 10,000 gallons of pool water at any one time. Source page (opens in a new browser tab)

    Also checked: Baquacil pH Decreaser: maker's directions on the Pool Geek retailer page Other source says: Never add more than 2 lb of Baquacil pH Decreaser per 10,000 gallons in a single treatment. Source page (opens in a new browser tab)

    Also checked: In The Swim: pH Reducer Other source says: Do NOT add more than 20 oz. of pH Reducer per 10,000 gallons of water at one time. Source page (opens in a new browser tab)

    Checked against the source on 11/10/2026. Re-opened by a second checker on 11/9/2026, who matched the source's words to this figure.

  • Most soda ash to add in one treatment: 4 lb per 10,000 US gal per stage Other source

    Leslie's: Soda Ash pH Up Other source says: Do not exceed 4 lbs per 10,000 gallons in a single treatment to avoid overcorrection. Source page (opens in a new browser tab)

    Checked against the source on 11/9/2026. Re-opened by a second checker on 11/9/2026, who matched the source's words to this figure. Looked up again on 11/10/2026 by a checker who couldn't see our figure: it came back with the same figure.

  • Do not let pH fall below this when adding acid: 7.2 pH Official

    Multnomah County (Oregon) Environmental Health: Water Treatment - Swimming Pools, EHS-0058 Official says: Do not allow pH to go below 7.2. Source page (opens in a new browser tab)

    Checked against the source on 11/9/2026. Re-opened by a second checker on 11/9/2026, who matched the source's words to this figure. Looked up again on 11/10/2026 by a checker who couldn't see our figure: it came back with the same figure.

  • Order of adjustments: total alkalinity, chlorine, pH, other (calcium, stabilizer, salt) Official

    Licking County Health Department (Ohio): Pool and Spa Water Chemistry Adjustment Guide Official says: if multiple chemical adjustments are required, adjust in the following order: 1) Total Alkalinity 2) Chlorine 3) pH 4) Other Adjustments. Source page (opens in a new browser tab)

    Also checked: Leslie's: Muriatic Acid 2-Pack (28%-32%) Other source says: Always adjust the Total Alkalinity first. Source page (opens in a new browser tab)

    Checked against the source on 11/9/2026. Re-opened by a second checker on 11/9/2026, who matched the source's words to this figure.

  • Circulate and wait before retesting after dry acid: at least 4 hours (our limit)

    Our limit, not this label's figure. The calculators wait at least 4 hours after acid before you retest pH. The Alliance Trading label below says 2 hours. We use the longer wait because it is the more cautious one: Leslie's dry acid page says to swim after 4 hours of circulation, and our calculators wait at least 4 hours between every step. Some product labels give 12 to 24 hours: follow your label if it says longer.

    Alliance Trading 'pH DOWN' label, sodium bisulfate 93.2% Other source says: Allow pool water to recirculate two hours and retest pH. Repeat treatment as necessary. Source page (opens in a new browser tab)

    Also checked: Leslie's: Dry Acid pH Down Other source says: You can swim after 4 hours of circulation Source page (opens in a new browser tab)

    Also checked: Baquacil pH Decreaser: maker's directions on the Pool Geek retailer page Other source says: Allow the water to circulate for 12 to 24 hours. Recheck your pH reading. Source page (opens in a new browser tab)

    Checked against the source on 11/10/2026. Re-opened by a second checker on 11/9/2026, who confirmed this source's 2 hours, in the words quoted here. Our longer limit shown above is our own choice; that check didn't cover it.

  • Wait before the next acid adjustment when lowering total alkalinity: 12 hours (at least; then retest alkalinity and pH) Official

    Indiana Department of Health: Adjusting Chemical Levels in a Swimming Pool / Water Chemistry Adjustment Guide Official says: If more acid than this is needed, then make one adjustment, and then retest 12 hours later before making another adjustment. Source page (opens in a new browser tab)

    Also checked: Alliance Trading 'pH DOWN' label, sodium bisulfate 93.2% Other source says: Allow pool water to recirculate two hours and retest pH. Repeat treatment as necessary. Source page (opens in a new browser tab)

    Also checked: Leslie's: Dry Acid pH Down Other source says: You can swim after 4 hours of circulation Source page (opens in a new browser tab)

    Also checked: Baquacil pH Decreaser: maker's directions on the Pool Geek retailer page Other source says: Allow the water to circulate for 12 to 24 hours. Recheck your pH reading. Source page (opens in a new browser tab)

    Checked against the source on 11/10/2026.

  • Circulation time stated on balancer products: 4 hours Other source

    Leslie's: Soda Ash pH Up Other source says: You can swim after 4 hours of circulation once the product is fully dissolved. Source page (opens in a new browser tab)

    Also checked: Leslie's: Alkalinity Up Other source says: Takes around 4 hours for full circulation of Alkalinity Up. Source page (opens in a new browser tab)

    Also checked: Leslie's: Dry Acid pH Down Other source says: You can swim after 4 hours of circulation Source page (opens in a new browser tab)

    Checked against the source on 11/9/2026. Re-opened by a second checker on 11/9/2026, who matched the source's words to this figure.

  • Run the pump after adding salt: 24 hours Other source

    Hayward AquaRite Owner's Manual 092538 RevD Other source says: Run the filter pump for 24 hours with the suction coming from the main drain (use pool vac if there is no main drain) Source page (opens in a new browser tab)

    Also checked: Hayward AquaRite Owner's Manual 092538 RevD Other source says: The salt display may take 24 hours to respond to the change in salt concentration. Source page (opens in a new browser tab)

    Checked against the source on 11/9/2026. Re-opened by a second checker on 11/9/2026, who matched the source's words to this figure.

  • New plaster pools: wait before adding salt: 10–14 days Other source

    Hayward AquaRite Owner's Manual 092538 RevD Other source says: For new plaster pools, wait 10-14 days before adding salt to allow the plaster to cure. Source page (opens in a new browser tab)

    Checked against the source on 11/9/2026. Re-opened by a second checker on 11/9/2026, who matched the source's words to this figure.

  • Chlorine (liquid, cal-hypo, dichlor, tablets, shock): when labels allow swimming: at or below your label's level Other source

    EPA-accepted label: B's Pool Supply Sodium Hypochlorite Solution 12.5% (EPA Reg. 55487-20001) Other source says: Do not enter treated pool above 4 ppm chlorine level due to risk of bodily harm. Source page (opens in a new browser tab)

    Also checked: EPA-accepted label: PDQ ChlorSan 8% Sodium Hypochlorite (EPA Reg. 58880-2) Other source says: Reentry into treated pools is prohibited above levels of 4.0 ppm due to risk of bodily harm. Source page (opens in a new browser tab)

    Also checked: HTH Pool Care Shock product page Other source says: Do not enter the pool until free available chlorine levels return to 1–4 ppm. Source page (opens in a new browser tab)

    Also checked: EPA-accepted label: Tarry trichlor 8 oz tablets/sticks (Qualco, EPA Reg. 3525-120) Other source says: Do not enter pool until the chlorine residual drops to 2.0 ppm (parts per million). Source page (opens in a new browser tab)

    Also checked: CDC Model Aquatic Health Code, 5th edition (2024), Code Official says: Maximum DPD-FC concentrations shall not exceed limits specified on the product label. Source page (opens in a new browser tab)

    Checked against the source on 11/9/2026. Re-opened by a second checker on 11/9/2026, who matched the source's words to this figure. Looked up again on 11/10/2026 by a checker who couldn't see our figure: it came back with the same figure.

  • Dry acid: wait before swimming (one product's own page): 4 hours of circulation Other source

    Leslie's: Dry Acid pH Down Other source says: You can swim after 4 hours of circulation Source page (opens in a new browser tab)

    Checked against the source on 11/9/2026. Re-opened by a second checker on 11/9/2026, who matched the source's words to this figure.

  • Soda ash: wait before swimming (one product's own page): 4 hours of circulation Other source

    Leslie's: Soda Ash pH Up Other source says: You can swim after 4 hours of circulation once the product is fully dissolved. Source page (opens in a new browser tab)

    Checked against the source on 11/9/2026. Re-opened by a second checker on 11/9/2026, who matched the source's words to this figure.

  • Baking soda: wait before swimming (one product's own page): once fully dissolved; about four hours of circulation (one maker) Other source

    Leslie's: Alkalinity Up Other source says: Takes around 4 hours for full circulation of Alkalinity Up. Source page (opens in a new browser tab)

    Checked against the source on 11/9/2026. Re-opened by a second checker on 11/9/2026, who matched the source's words to this figure.

  • Muriatic acid: wait before swimming: no published figure found Not confirmed

    We couldn't find a published figure for this. Follow your product's label, or ask a pool professional.

    Closest we found: Virginia Department of Health says NEVER add pool chemicals when the pool is in use, and only add them poolside as directed by the product label. Source page (opens in a new browser tab)

  • Calcium chloride: wait before swimming: no published figure found Not confirmed

    We couldn't find a published figure for this. Follow your product's label, or ask a pool professional.

    Closest we found: Virginia Department of Health says NEVER add pool chemicals when the pool is in use, and only add them poolside as directed by the product label. Source page (opens in a new browser tab)

  • Stabilizer (cyanuric acid): wait before swimming: no published figure found Not confirmed

    We couldn't find a published figure for this. Follow your product's label, or ask a pool professional.

    Closest we found: Virginia Department of Health says NEVER add pool chemicals when the pool is in use, and only add them poolside as directed by the product label. Source page (opens in a new browser tab)

  • Salt: wait before swimming: no published figure found Not confirmed

    We couldn't find a published figure for this. Follow your product's label, or ask a pool professional.

    Closest we found: Virginia Department of Health says NEVER add pool chemicals when the pool is in use, and only add them poolside as directed by the product label. Source page (opens in a new browser tab)

  • Average depth = (shallow end + deep end) / 2: shallow end plus deep end, halved Official

    City of Akron (Ohio) water: How to calculate the gallons in a swimming pool Official says: 2' + 10' = 12'; 12'/2 = 6' Average Depth Source page (opens in a new browser tab)

    Also checked: a water utility's pool calculator page (no publisher named) Other source says: Average depth = ( 3 + 9 ) / 2 = 6 feet. Source page (opens in a new browser tab)

    Checked against the source on 11/9/2026. Re-opened by a second checker on 11/9/2026, who matched the source's words to this figure.

  • Rectangle: length x width x average depth x 7.5 = US gallons: 7.5 US gal per cubic ft (multiplier) Official

    City of Oregon City (Oregon): Swimming Pool Water Estimator Official says: Take the length time’s width, times the average depth, times 7.5. Source page (opens in a new browser tab)

    Also checked: City of Akron (Ohio) water: How to calculate the gallons in a swimming pool Official says: Length * Width * Average Depth * Multiplier = Gallons Source page (opens in a new browser tab)

    Also checked: Pentair IntelliChlor IC15/20/40/60 Installation and User's Guide, P/N 520589 Rev R Other source says: Rectangular Pools: Length x width x average depth x 7.5 Source page (opens in a new browser tab)

    Also checked: a water utility's pool calculator page (no publisher named) Other source says: 25.75 ft x 10 ft x 6 ft x 7.5 = 11,587.5 gallons Source page (opens in a new browser tab)

    Also checked: NIST Special Publication 811, Appendix B.8 conversion factors Official says: cubic foot (ft3) to cubic meter (m3) 2.831 685 E-02; gallon (U.S.) (gal) to cubic meter (m3) 3.785 412 E-03 Source page (opens in a new browser tab)

    Checked against the source on 11/9/2026. Re-opened by a second checker on 11/9/2026, who matched the source's words to this figure. Looked up again on 11/10/2026 by a checker who couldn't see our figure: it came back with the same figure.

  • Round: diameter x diameter x average depth x 5.9 = US gallons: 5.9 multiplier Official

    City of Oregon City (Oregon): Swimming Pool Water Estimator Official says: Take the Diameter times Diameter, times the average depth, times 5.9. Source page (opens in a new browser tab)

    Also checked: City of Akron (Ohio) water: How to calculate the gallons in a swimming pool Official says: Length * Width * Average Depth * Multiplier = Gallons Source page (opens in a new browser tab)

    Also checked: Leslie's: Calculating pool volume Other source says: 3.14 × Radius × Radius × Average Depth × 7.5 = volume (gallons) Source page (opens in a new browser tab)

    Checked against the source on 11/9/2026. Re-opened by a second checker on 11/9/2026, who matched the source's words to this figure. Looked up again on 11/10/2026 by a checker who couldn't see our figure: it came back with the same figure.

  • Oval: length x width x average depth x 5.9 = US gallons: 5.9 multiplier Official

    City of Oregon City (Oregon): Swimming Pool Water Estimator Official says: Take the length time’s width, times the average depth, times 5.9. Source page (opens in a new browser tab)

    Also checked: City of Akron (Ohio) water: How to calculate the gallons in a swimming pool Official says: Length * Width * Average Depth * Multiplier = Gallons Source page (opens in a new browser tab)

    Also checked: Leslie's: Calculating pool volume Other source says: 3.14 × Length × Width × 0.25 × Average Depth × 7.5 = approximate volume (gallons) Source page (opens in a new browser tab)

    Also checked: Pentair IntelliChlor IC15/20/40/60 Installation and User's Guide, P/N 520589 Rev R Other source says: Oval Pools: Length x width x average depth x 6.7 Source page (opens in a new browser tab)

    Checked against the source on 11/9/2026. Re-opened by a second checker on 11/9/2026, who matched the source's words to this figure.

  • Kidney: 0.45 x (A + B) x length x average depth x 7.5 = US gallons (A, B = widths at the two widest points): 0.45 shape factor Other source

    a water utility's pool calculator page (no publisher named) Other source says: 0.45 x (A+B) x length x average depth x 7.5 = volume (in gallons) Source page (opens in a new browser tab)

    Also checked: Leslie's: Calculating pool volume Other source says: (A + B) × Length × 0.45 × Average Depth × 7.5 = approximate volume (gallons) Source page (opens in a new browser tab)

    Checked against the source on 11/9/2026. Re-opened by a second checker on 11/9/2026, who matched the source's words to this figure.

  • Irregular / free-form: longest length x widest width x average depth x 5.9 = US gallons: 5.9 multiplier Other source

    Leslie's: Calculating pool volume Other source says: Longest Length × Widest Width × Average Depth × 5.9 = approximate volume (gallons) Source page (opens in a new browser tab)

    Also checked: City of Akron (Ohio) water: How to calculate the gallons in a swimming pool Official says: Length * Width * Average Depth * Multiplier = Gallons Source page (opens in a new browser tab)

    Checked against the source on 11/9/2026. Re-opened by a second checker on 11/9/2026, who matched the source's words to this figure.

  • Sloping sides: multiply total US gallons by 0.85: 0.85 multiplier (optional) Other source

    Pentair IntelliChlor IC15/20/40/60 Installation and User's Guide, P/N 520589 Rev R Other source says: Sloping sides: Multiply total gallons by 0.85 Source page (opens in a new browser tab)

    Checked against the source on 11/9/2026.

  • US gallon to liters: 3.785412 L per US gal Official

    NIST Special Publication 811, Appendix B.8 conversion factors Official says: gallon (U.S.) (gal) | liter (L) | 3.785 412 | E+00 Source page (opens in a new browser tab)

    Checked against the source on 11/9/2026. Re-opened by a second checker on 11/9/2026, who matched the source's words to this figure.

  • Foot to meters (exact): 0.3048 m per ft Official

    NIST Special Publication 811, Appendix B.8 conversion factors Official says: foot (ft) | meter (m) | 3.048 | E-01 Source page (opens in a new browser tab)

    Checked against the source on 11/9/2026. Re-opened by a second checker on 11/9/2026, who matched the source's words to this figure.

  • US fluid ounce to milliliters: 29.57353 mL per US fl oz Official

    NIST Special Publication 811, Appendix B.8 conversion factors Official says: ounce (U.S. fluid) (fl oz) | milliliter (mL) | 2.957 353 | E+01 Source page (opens in a new browser tab)

    Checked against the source on 11/9/2026. Re-opened by a second checker on 11/9/2026, who matched the source's words to this figure.

  • Ounce (avoirdupois) to grams: 28.34952 g per oz Official

    NIST Special Publication 811, Appendix B.8 conversion factors Official says: ounce (avoirdupois) (oz) | gram (g) | 2.834 952 | E+01 Source page (opens in a new browser tab)

    Checked against the source on 11/9/2026. Re-opened by a second checker on 11/9/2026, who matched the source's words to this figure.

  • Pound to kilograms: 0.4535924 kg per lb Official

    NIST Special Publication 811, Appendix B.8 conversion factors Official says: pound (avoirdupois) (lb) | kilogram (kg) | 4.535 924 | E-01 Source page (opens in a new browser tab)

    Checked against the source on 11/9/2026. Re-opened by a second checker on 11/9/2026, who matched the source's words to this figure.

  • You should be able to see the drain at the bottom of the deep end: the drain at the bottom of the deep end can be seen Official

    CDC healthy swimming infographic: inspection Official says: Drain at the bottom of the deep end is visible. Source page (opens in a new browser tab)

    Also checked: Licking County Health Department (Ohio): Pool and Spa Water Chemistry Adjustment Guide Official says: Clarity Deepest point of pool visible from deck Source page (opens in a new browser tab)

    Checked against the source on 11/9/2026. Re-opened by a second checker on 11/9/2026, who matched the source's words to this figure.