How much chlorine to add to your pool

Doses checked 11/10/2026

It depends on your pool size, your product's strength, and how far free chlorine is below its target, which goes up with your stabilizer reading. The calculator aims for at least 2 ppm, or about 7.5% of your stabilizer reading if that is higher (industry guidance from a pool chemical maker and a trade magazine), and never above 4 ppm, the swimming level on most labels we checked. Add it with the pump running, wait at least 4 hours, then retest.

Your pool and readings

Pool size

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

How the water looks

Type of pool

Chlorine you have

Checked on every build: 82 tests of the sums this calculator runs, including 8 amounts printed in published charts, labels and manuals (ours must match them, or land under them where we start low on purpose) and 23 tests of its limits: caps, smaller rounds, and the cases where it gives no amount.

Read before you add anything

Never add acid and chlorine at the same time, and never mix them, even in a bucket or feeder. Mixing chlorine products with acid can create toxic gas. Add one, let the pump run, retest, then add the other.
Always add the chemical to water, never water to the chemical.
Add one chemical at a time. Never mix chemicals together, and use a separate clean scoop for each.
Add chemicals only when nobody is in the pool.
Wear the protective gear your product label asks for, such as goggles and gloves.
Handle chemicals in a well-ventilated area.
Add acid with the pump running, into the deep end, away from the skimmer and away from any floater or feeder that holds chlorine tablets.
Never add shock (cal-hypo or any other chlorine product) through the skimmer, or through any floater or feeder that holds or has held tablets, and never put different chlorine products in the same feeder.
Only pre-dissolve a chemical in a bucket if its label tells you to.
Store chemicals in a secure place away from children and pets, and never store liquid chemicals above dry chemicals.
Read the product label before each use. If the label differs from this estimate, follow the label.
These amounts are estimates. Add in stages and retest before adding more.
This tool cannot tell you the water is safe to swim in. Follow your product label, and if in doubt ask a pool professional.

Where each line comes from

CDC, Using Pool Chemicals Safely Official: “Never mix / Chlorine products with acid; this could create toxic gases” Source page (opens in a new browser tab)
12.5% liquid chlorine label, EPA-accepted Other source: “Mixing this product with chemicals (e.g. ammonia, acids, detergents, etc.) or organic matter (e.g. urine, feces, etc.)” ... “will release chlorine gas which is irritating to eyes, lungs and mucous membranes.” Source page (opens in a new browser tab)
CDC Official: “add pool chemical to water; NEVER add water to pool chemical” and “violent (potentially explosive) reaction can occur” Source page (opens in a new browser tab)
Virginia Department of Health Official: “Add chemicals to water - not water to chemicals.” Source page (opens in a new browser tab)
Indiana Department of Health Official: “Add acids to water, NEVER water to acid. Remember AAA (Always Add Acid).” Source page (opens in a new browser tab)
CDC Model Aquatic Health Code 2024, 5.9.3.4.2.3.1 Official: “Two or more chemicals shall never be mixed in the same dilution water.” Source page (opens in a new browser tab)
Indiana Official: “Never mix any chemicals together.” Source page (opens in a new browser tab)
Virginia Official: “Designate tools per chemical - Do not use the same scoop for different chemicals.” Source page (opens in a new browser tab)
MAHC 5.9.3.4.1.2 Official: “Chemicals added manually directly into the AQUATIC VENUE shall only be introduced in the absence of BATHERS.” Source page (opens in a new browser tab)
Virginia Official: “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)
CDC, Using Pool Chemicals Safely Official: “Dress for safety by wearing appropriate safety equipment (for example, safety goggles, gloves, and mask)” Source page (opens in a new browser tab)
12.5% liquid chlorine label, EPA-accepted Other source: “Wear safety glasses or goggles and rubber gloves when handling this product.” Source page (opens in a new browser tab)
Alliance Trading pH Down (dry acid) label Other source: “Wear goggles or safety glasses and rubber gloves when handling this product.” Source page (opens in a new browser tab)
CDC, Using Pool Chemicals Safely Official: “Handle in a well-ventilated area” Source page (opens in a new browser tab)
Leslie's muriatic acid Other source: “With the pump running, pour the solution into the deep end of your pool, or away from the skimmer or any fixtures.” Source page (opens in a new browser tab)
Alliance Trading pH Down label Other source: “To add this product, broadcast into the deep end of the pool when not in use.” and “Do not add near metal fittings nor allow pH to drop below 7.2.” Source page (opens in a new browser tab)
CDC Official: “Never mix / Chlorine products with acid; this could create toxic gases” Source page (opens in a new browser tab)
UConn Health, Connecticut Poison Control Center, "Splish Splash Safety" Other source: “Keep acids away from other chemicals.” Source page (opens in a new browser tab)
Alliance Chemical 12.5% sodium hypochlorite safety data sheet Other source: “Never mix with acids, ammonia or other cleaning products: this releases toxic chlorine or chloramine gas.” Source page (opens in a new browser tab)
HTH Pool Care Shock, calcium hypochlorite 52% Other source: “Do not use this product in a floater or feeder.” Source page (opens in a new browser tab)
HTH 3" Chlorine Tabs Advanced Other source: “Do not use this product in floaters or feeders that have been used with other chlorinating products.” and “Do not use with any other tablets or sticks in the same skimmer, floater, or feeder.” Source page (opens in a new browser tab)
BioGuard cal-hypo label, EPA-accepted Other source: “Do not add this product to any dispensing device containing remnants of any other product.” Source page (opens in a new browser tab)
CDC Official, under “Never mix”: “Different pool chemicals (for example, different types of chlorine products) with each other or with any other substance” Source page (opens in a new browser tab)
CDC Official: “Only pre-dissolve pool chemicals when directed by product label” Source page (opens in a new browser tab)
Virginia Official: “Store chemicals in secure location away from children and pets.” Source page (opens in a new browser tab)
Virginia Official: “Never store liquid chemicals above dry chemicals.” Source page (opens in a new browser tab)
CDC Official: “Read chemical product label before each use” Source page (opens in a new browser tab)
Yakima County chart Official: “NOTE: This chart gives approximate amounts of each chemical listed. Always read the labels for exact” / “amounts needed for your chemical adjustments.” Source page (opens in a new browser tab)
Licking County Official: “Always follow instructions on the manufactures label for exact dosage amounts and handling.” Source page (opens in a new browser tab)
Multnomah County Official: “It is always better to add part of the required amount of chemical over several occasions” ... “than all at once (EXCEPTION: breakpoint chlorination).” Source page (opens in a new browser tab)
Indiana Official: “Add large amounts gradually in thirds over a 2-hour period.” Source page (opens in a new browser tab)
Our own rule for every result: we point you to your label and the official guidance instead.

How much each product adds

Amount that raises free chlorine by one ppm in 10,000 US gallons
Product	Amount	Where it comes from
Liquid chlorine 6%	17.78 US fl oz	Worked out from the label strength and the liquid's weight
Liquid chlorine 8.25%	12.93 US fl oz	Worked out the same way
Liquid chlorine 10%	10.67 US fl oz	Worked out the same way
Liquid chlorine 12.5%	8.53 US fl oz	Worked out the same way
Cal-hypo 65%	2 oz	Multnomah County (Oregon) Environmental Health chart: GRANULAR 65% 2 oz. 1ppm.
Dichlor 56%	2.32 oz	Worked out from the Indiana Department of Health rule; its chart row says Dichlor (56%) 2.4 oz 12 oz 1.4 lbs.

Liquid chlorine: the strength on the label is by weight, and the liquid is heavier than water. One maker's safety data sheet gives Relative Density 1.195 at 20/20 °C (water = 1), so the calculator divides by 1.2. That gives less than most charts, such as the Indiana Department of Health row Sodium Hypochlorite (12%) 10.7 fl.oz. 1.7 qts 3.3 qts. We start lower on purpose, so retest free chlorine before anyone swims.

Dry chlorine: the calculator uses the Indiana Department of Health rule, 1.0 ppm equals about .083 lbs of chemical per 10,000 gallons of water* or 1.3 oz per 10,000 gallons**. and divides it by your product's strength. Leave the strength empty and it assumes the strongest product we accept, so the amount comes out low rather than high.

For example, say your pool holds 20,000 US gallons, free chlorine reads 1 ppm, stabilizer is 30 ppm, and you have liquid chlorine at 10%. The target is 2.5 ppm, and the calculator says to add 1 US qt (32 US fl oz) (945 mL), then wait and retest.

How many chlorine tablets

Choose tablets in the calculator and it works out whole tablets a week (3-inch trichlor tablets) from the label rate, rounded down. One maker's page 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. Another label says Suggested dosage is one {tablet}{stick} per 11,500 gallons of pool water per week. Type your own label's figure if it differs.

If your pool is smaller than one tablet's label rate, the calculator tells you not to use a whole tablet, and to use a product whose label covers your pool size. Never add shock (cal-hypo or any other chlorine product) through the skimmer, or through any floater or feeder that holds or has held tablets, and never put different chlorine products in the same feeder.

Tablets add stabilizer as they dissolve. The PHTA pool industry committee says When trichlor is used, 0.6 ppm of cyanuric acid is added to the water for each ppm of available chlorine added. Dichlor adds about 1 ppm of stabilizer for each ppm of chlorine, by the county charts. Test stabilizer regularly if you use either.

Why the target depends on stabilizer

Stabilizer protects chlorine in outdoor pools from sunlight, and the more stabilizer there is, the more free chlorine you need. A pool chemical maker and a trade magazine give about 7.5% of the stabilizer reading, and the calculator uses that. Oregon's official floor is lower: the Oregon Health Authority says Exceeding the CYA to free chlorine ratio of 45:1 means the chlorine is unable to kill pathogens in the water. That works out at about 2.2%. The calculator aims for about 7.5% of your stabilizer reading, never less than 2 ppm and never above 4 ppm. The chart on how to raise free chlorine shows the target for each stabilizer reading.

How to add chlorine

Test free chlorine and stabilizer.
Put on the protective gear your label asks for, such as goggles and gloves. Make sure nobody is in the pool, and run the pump.
Add the amount as your label directs. Never add it through the skimmer, or through any floater or feeder that holds or has held tablets. Add nothing else at the same time.
Wait at least 4 hours with the pump running, then retest.
Swim only once free chlorine is at or below the level on your product's label.

Questions people ask

How much chlorine do I add to my pool?

Enough to bring free chlorine up to its target: at least 2 ppm, more with stabilizer, never above 4 ppm. The amount depends on your pool size and product, which is what the calculator works out.

How much liquid chlorine do I add to my pool?

By our figures, 10.67 US fl oz of liquid chlorine 10% raises free chlorine by one ppm in 10,000 US gallons. Multiply by the ppm you need and by your pool size in units of 10,000 US gallons, or the calculator will work it out for you.

How many chlorine tablets does my pool need?

One maker's page 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. The calculator works out whole tablets a week from your label's rate, rounded down.

How do I add chlorine to my pool?

With nobody in the pool and the pump running, add it as your label directs, never through a skimmer, floater or feeder that holds or has held tablets. Wait at least 4 hours, then retest.

When can I swim after adding chlorine?

Once free chlorine is at or below your label's level. A liquid chlorine label we checked says SWIMMING POOL WATER DISINFECTION – Do not reenter pool with a chlorine level above 4 ppm for risk of bodily harm. One tablet label says Do not enter pool until the chlorine residual drops to 2.0 ppm (parts per million).

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The charts behind this page

Show all 26 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.
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.
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.
Liquid chlorine 6%: US fl oz to raise free chlorine 1 ppm in 10,000 US gal: 17.78 US fl oz per ppm per 10,000 US gal Other source (worked out)
Worked out: 128 ÷ (6 × 1.2) = 17.78
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: 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)
Checked against the source on 11/9/2026.
Liquid chlorine 8.25%: US fl oz to raise free chlorine 1 ppm in 10,000 US gal: 12.93 US fl oz per ppm per 10,000 US gal Other source (worked out)
Worked out: 128 ÷ (8.25 × 1.2) = 12.93
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: 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: 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)
Checked against the source on 11/9/2026.
Liquid chlorine 10%: US fl oz to raise free chlorine 1 ppm in 10,000 US gal: 10.67 US fl oz per ppm per 10,000 US gal Other source (worked out)
Worked out: 128 ÷ (10 × 1.2) = 10.67
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: 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: 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: Yakima County (Washington): Chemical Dosing chart Official says: Sodium Hypochlorite (Bleach) 13 fluid ounces 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)
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 12.5%: US fl oz to raise free chlorine 1 ppm in 10,000 US gal: 8.53 US fl oz per ppm per 10,000 US gal Other source (worked out)
Worked out: 128 ÷ (12.5 × 1.2) = 8.53
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: 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: 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)
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.
Cal-hypo 65%: oz to raise free chlorine 1 ppm in 10,000 US gal: 2 oz per ppm per 10,000 US gal Official (worked out)
Worked out: 1.3 ÷ 0.65 = 2.0 (matches all four charts)
Multnomah County (Oregon) Environmental Health: Water Treatment - Swimming Pools, EHS-0058 Official says: GRANULAR 65% 2 oz. 1ppm Source page (opens in a new browser tab)
Also checked: Yakima County (Washington): Chemical Dosing chart Official says: Calcium Hypochlorite 2.0 ounces Source page (opens in a new browser tab)
Also checked: Salt Lake County Health Department (Utah): pool chemical dosages Official says: Calcium Hypochlorite 2 oz. 10 oz. 20 oz. 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)
Checked against the source on 11/9/2026.
Dichlor 56%: oz to raise free chlorine 1 ppm in 10,000 US gal: 2.32 oz per ppm per 10,000 US gal Official (worked out)
Worked out: 1.3 ÷ 0.56 = 2.32
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: 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 2 ½ oz. 12 ½ oz. 25 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 own words quoted here.
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.
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.
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.
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.
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.