How to lower total alkalinity in your pool

Doses checked 11/10/2026

Add acid in rounds and retest between them. The official charts from the Indiana Department of Health (opens in a new browser tab) and Licking County, Ohio (opens in a new browser tab) give about 26 US fl oz of muriatic acid 31.45% (hydrochloric acid) to lower alkalinity by 10 ppm in 10,000 US gallons. The calculator starts lower on purpose, so you may need more than one round. After each round, wait at least 12 hours, then retest alkalinity and pH.

Checked on every build: 40 tests of the sums this calculator runs, including 5 amounts printed in published charts, labels and manuals (ours must match them, or land under them where we start low on purpose) and 15 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 acid lowers alkalinity

Amounts to lower total alkalinity by 10 ppm in 10,000 US gallons
Acid	Official charts	The calculator starts with	Most at one time
Muriatic acid 31.45%	26 US fl oz	16 US fl oz	13 US fl oz
Dry acid (sodium bisulfate), also sold as pH minus	2.1 to 2.3 lb	2 lb	1.5 lb
Muriatic acid 14.5%	No published figure found	No amount: follow your bottle	Follow your bottle's label

Why the calculator starts lower: when sources differ, we use the smaller amount and you retest, because too much acid takes another chemical to undo, while too little only needs another round. Leslie's, which sells its own muriatic acid, says 2 cups of Muriatic Acid will lower Total Alkalinity by 10 ppm in 10,000 gallons of water. The official charts say more, so go by your retests.

Dry acid: Indiana Department of Health gives 2.1 lb and Multnomah County (Oregon) Environmental Health 2.3 lb; the calculator starts with Leslie's 2 lb: 2 lbs of Leslie's Dry Acid will decrease Total Alkalinity by 10 ppm in 10,000 gallons of water.

Most at one time: the Indiana Department of Health (opens in a new browser tab) says Do not add more than one quart of acid per 10,000 gallons at one time. The calculator keeps each round to 13 US fl oz per 10,000 US gallons, the cautious reading of a maker's Never add more than 16 oz per 10,000 gallons at one time. For dry acid, the label says Never add more than 1.5 pounds of this product per 10,000 gallons of pool water at any one time. Each round is also kept small enough that, by our pH chart, pH should not fall below 7.2.

For example, say your pool holds 20,000 US gallons, total alkalinity is 150 ppm and pH is 7.8. The calculator says to add 26 US fl oz (765 mL) of muriatic acid now, then wait at least 12 hours and retest alkalinity and pH. In all, it estimates 3 US qt (96 US fl oz) by its starting figure, and up to 1.21 US gal (156 US fl oz) by the official charts.

Wait at least 12 hours between rounds

The Indiana Department of Health (opens in a new browser tab) says If more acid than this is needed, then make one adjustment, and then retest 12 hours later before making another adjustment. That is the only official wait we found for acid used on alkalinity, so the calculator uses it. Makers differ: one label says Allow pool water to recirculate two hours and retest pH. Repeat treatment as necessary. and another Allow the water to circulate for 12 to 24 hours. Recheck your pH reading. Follow your product's label if it says longer. Keep the pump running while you wait.

If pH is already low

If alkalinity is high but pH is below 7.4, the calculator gives no acid amount and sends you to a pool professional: acid would push pH lower still, and Multnomah County (Oregon) Environmental Health says Do not allow pH to go below 7.2.

Add some, wait, retest

Test total alkalinity and pH.
Put on the protective gear your acid's label asks for, such as goggles and gloves. Make sure nobody is in the pool, and run the pump.
Add one round of acid into the deep end, away from the skimmer and away from any floater or feeder that holds chlorine tablets. Add nothing else at the same time.
Wait at least 12 hours with the pump running, then retest alkalinity and pH.
Work out the next round from your new readings. Stop once alkalinity is at or below 120 ppm, the top of the band in the Licking County Health Department (Ohio) chart, and never let pH fall below 7.2.

Vinyl, fiberglass and painted pools

Check your acid's label first. One maker, Leslie's, says: “Muriatic Acid is not recommended for use on fiberglass, vinyl liner, or painted pools.”

Waiting to swim: for its dry acid, Leslie's says You can swim after 4 hours of circulation, and only once free chlorine and pH are back within your label's range. For muriatic acid: We couldn't find a published figure for this. Follow your product's label, or ask a pool professional.

Questions people ask

How do I lower the alkalinity in my pool?

Add muriatic acid or dry acid in rounds, into the deep end with the pump running. Wait at least 12 hours after each round, then retest alkalinity and pH before adding more.

How much muriatic acid lowers alkalinity?

Official charts give about 26 US fl oz of muriatic acid 31.45% to lower alkalinity by 10 ppm in 10,000 US gallons. The calculator starts with 16 US fl oz on purpose, so you may need more than one round.

Why does the calculator give less acid than the chart?

When sources differ, we start with the smaller amount and you retest. Too much acid takes another chemical to undo; too little only needs another round.

What counts as high alkalinity?

Above 120 ppm is above the band the calculator aims for, 80–120 ppm. CDC's model code for public pools allows up to 180 ppm. Above 240 ppm the calculator sends you to a pool professional.

Does lowering alkalinity lower pH too?

Yes. Acid lowers pH as well, which is why the calculator needs your pH reading and keeps each round small enough that pH should stay at or above 7.2.

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The charts behind this page

Show all 19 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.

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.
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.
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.
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.
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.
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.
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.
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)
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.