pH & Alkalinity Balance Calculator
Choose what you want to adjust, enter your pool volume and current/target readings, and get an estimated chemical dose. Guidance only — dose gradually and re-test with a kit.
Chemical to add
How the dose is estimated
Each estimate is built from a standard rule-of-thumb dosing rate published across pool-chemistry references, scaled by your pool volume and how far you want to move the reading: roughly 6 oz of soda ash per 10,000 gallons raises pH about 0.2, roughly 25 fl oz of 31.45% muriatic acid per 10,000 gallons lowers pH about 0.2, and roughly 1.5 lb of baking soda per 10,000 gallons raises total alkalinity by about 10 ppm.
These are planning estimates, not an exact titration — actual response depends on your water’s existing alkalinity, temperature, and how thoroughly the chemical circulates, so treat the number as a starting dose and confirm with a retest.
Frequently Asked Questions
What pH and total alkalinity should a pool be kept at?
CDC gives pH 7.0 to 7.8 (this calculator refuses targets outside it), with 7.4-7.6 often cited as ideal because it's close to the pH of human eyes and skin, and it's the range where chlorine works most efficiently without becoming overly harsh. Total alkalinity is typically kept around 80-120 ppm, since it acts as a buffer that keeps the pH from swinging wildly whenever something is added to the water.
Why do pH and alkalinity affect each other?
Total alkalinity measures the water's resistance to pH change. When alkalinity is low, pH tends to bounce around unpredictably after every chemical addition or heavy bather load; when it's very high, pH tends to drift upward on its own and becomes hard to lower. That's why pool guides usually recommend getting total alkalinity into range first, then fine-tuning pH.
Will raising alkalinity change my pH too?
Yes — baking soda (sodium bicarbonate) nudges pH upward slightly as a side effect of raising alkalinity, and muriatic acid used to lower pH will also pull alkalinity down somewhat. This calculator estimates each adjustment independently; after dosing, re-test both readings before deciding whether a second, smaller correction is needed.
Is it better to dose all at once or gradually?
Gradually. Large single doses of pH or alkalinity chemicals can overshoot the target, cause cloudiness, or (with acid) create a strong localized concentration near where it's poured. Add a portion of the estimated amount, circulate the water, wait for the manufacturer's recommended retest interval, and adjust from there.
Dosing guidance only, not a substitute for the manufacturer's instructions or a professional water test. Pool chemicals can be hazardous, especially acids — read and follow the product label, add chemicals to water (never water to chemical), never mix different products together, and keep them out of reach of children and pets.
Before you add any chemical
- CDC: "Read product label before each use" and follow it. The label, not this calculator, sets the dose and the strength.
- CDC: "Never mix: Chlorine products with acid; this could create toxic gases." Never mix different pool chemicals, including different types of chlorine, with each other or with anything else.
- Add the chemical to water, never water to the chemical. CDC: "NEVER add water to the pool chemical because a violent (potentially explosive) reaction can occur."
- Store each chemical separately, closed in its original labeled container, below 95°F (35°C). CDC: "Separate incompatible chemicals (for example, acid and chlorine)." and "Keep chemicals secure and away from children and pets."
- CDC ranges: "The typical range is 1-4 ppm for chlorine" and pH 7.0 to 7.8. Test chlorine and pH before anyone swims, and at least twice a day while the pool is in use (CDC).
- Doses here round DOWN and assume US gallons (a UK gallon is 1.2 US gallons). Add part, circulate, re-test, and keep everyone out of the water until the test reads inside the range.
Pool safety comes first
- Pool Safely (CPSC): "A fence of at least four feet in height should surround the pool or spa on all sides and should not be climbable for children." Fence all four sides, separating the pool from the house, with self-closing, self-latching gates (CDC).
- Pool Safely: "Always watch children when they’re in or near water, and never leave them unattended." Name one adult as the Water Watcher.
- Drain covers: Pool Safely says "never enter a pool or spa that has a loose, broken or missing drain cover." Powerful drain suction "can even trap an adult". Public pools and spas must meet the Virginia Graeme Baker Pool & Spa Safety Act.
- Pumps, heaters and other pool equipment need GFCI protection, and CPSC says to "Have an electrician who is qualified in pool and spa repairs inspect and upgrade your pool, spa or hot tub".
- CDC: hot tub "Water temperature should not be higher than 104°F (40°C)."