How much to add, from your test results
Pick the reading that's off. You'll get the amount in pounds and ounces of the product you have, worked out for your pool's gallons.
- Free chlorineLow, or zero after a storm
- pHToo high or too low
- AlkalinitypH keeps drifting
- Stabilizer (CYA)Chlorine burns off fast
- SaltSalt cell says low
- ShockGreen, cloudy or smelly
Don't know your gallons? Start with the pool size calculator.
All calculators
All free to use.
- Pool Volume CalculatorHow many gallons your pool holds, for rectangle, round, oval and kidney pools.
- Pool Chlorine CalculatorRaise free chlorine with liquid chlorine, bleach, cal-hypo, dichlor or trichlor.
- Pool Shock CalculatorThe shock dose for breaking down combined chlorine (the chlorine smell and cloudy water).
- Pool Salt CalculatorHow many pounds and 40-lb bags of salt to reach your salt cell's target level.
- Pool pH CalculatorSoda ash to raise pH, or muriatic or dry acid to lower it.
- Pool Alkalinity CalculatorBaking soda to raise total alkalinity, or acid to bring it down.
- Pool Stabilizer CalculatorHow much stabilizer (cyanuric acid, CYA) to add, or how much water to drain if it's too high.
- Hot Tub Chemical CalculatorChlorine, pH and alkalinity amounts sized for a hot tub's small volume.
Guides
- Ideal chemistry levels chartTarget ranges for chlorine pools, salt pools and hot tubs, with sources.
- Recommended pool and hot tub suppliesTest kits, robotic cleaners, salt systems, covers and brushes, each with the review it came from.
- How long after shocking a pool can you swim?When it's safe to swim after shocking a pool: the chlorine level on your shock's label, how to test it, and why non-chlorine shock is different.
- How to clear a green poolGreen pool water means algae. To clear it, balance pH, brush, shock, run the filter nonstop and vacuum. Amounts for your pool size are below.
- Why is my pool cloudy? Causes and fixesCloudy pool water usually comes from the filter, low chlorine, high pH or early algae. Find which you have and fix it, plus clarifier vs flocculant.
- Why pool chlorine reads low after shockingShocked the pool and chlorine still reads low or zero? The usual causes are sun, algae, too much or too little stabilizer, weak chlorine or a test error.
- How to lower pH in a poolHow to lower pool pH with muriatic acid or dry acid: how much to add for your pool size, how to add acid safely, and why pH keeps creeping back up.
Printables
Each prints on one page.
- Weekly Pool Water Test LogOne page a week for your readings and what you added, with target ranges printed on it.
- Pool Opening ChecklistEvery step from pulling the cover to the first swim, in order.
- Pool Closing ChecklistBalance, winterize the plumbing and equipment, and cover the pool.
- Pool Chemical Dosing Chart by Pool SizeDoses for chlorine, pH, alkalinity, stabilizer and salt, for pools from 5,000 to 40,000 gallons.
How we check the numbers
Every formula on this site is checked against at least two published references, like manufacturer technical data and university extension guides. Each calculator shows its math and lists those sources, so you can check it yourself.