Pool Chemistry Calculators & Guides
Free calculators for every dose. Plain-language guides for every problem. The chemistry behind the numbers, explained.
Free pool calculators
Calculate the right dose before you add a drop.
Pool Volume Calculator
Find your gallons. The starting point for every accurate dose.
Calculate →Chlorine Dose Calculator
How much liquid chlorine to raise FC to your target.
Calculate →Pool Shock Calculator
Correct dose to clear algae or reach breakpoint chlorination.
Calculate →Pool pH Calculator
Raise or lower pool pH: muriatic acid or soda ash, calculated dose.
Calculate →Muriatic Acid Calculator
Lower pH or total alkalinity without overshooting.
Calculate →Baking Soda Calculator
Raise total alkalinity without a big pH spike.
Calculate →CYA Dilution Calculator
How much water to drain and refill to bring CYA down.
Calculate →LSI Calculator
Is your water balanced, corrosive, or scaling? The full calculation.
Calculate →Saltwater Pool Salt Calculator
How many pounds of pool salt to add to reach your SWG's target ppm.
Calculate →Calcium Hardness Calculator
How much calcium chloride to raise CH to target for proper water balance.
Calculate →Chemical Addition Order Calculator
Multiple things out of range? Get a step-by-step workflow: estimated doses, suggested order, wait times between steps.
Get my plan →Dry Acid Calculator
Convert between dry acid (sodium bisulfate) and muriatic acid doses.
Calculate →Pool Opening Calculator
Your spring shopping list: shock, pH, alkalinity, calcium, and CYA doses for your pool.
Calculate →Pool Closing Calculator
Winterizing chemical amounts for your pool size and current readings.
Calculate →Water Replacement Calculator
How much to drain and refill to fix CYA, calcium, or salt.
Calculate →Chlorine Usage Calculator
How much liquid chlorine your pool uses per week, and what it costs per month.
Calculate →Chlorine Cost Calculator
Liquid vs tablets vs cal-hypo: the real seasonal cost, including CYA buildup.
Calculate →Overnight Chlorine Loss Test
Enter dusk and dawn FC readings for a pass/fail verdict on hidden algae.
Calculate →What's wrong with your pool?
Pick a symptom to get the diagnosis and the fix.
Understand the chemistry
Know the why behind the numbers, so the fix actually makes sense.
What Is Free Chlorine?
The only chlorine that sanitizes. What FC measures, why it drops, and what level you actually need.
Read the explainer →Cyanuric Acid (CYA) Explained
CYA shields chlorine from UV, but too much makes it ineffective. The range that actually works.
Read the explainer →Total Alkalinity Explained
Alkalinity is pH's shock absorber. Too low and pH swings wildly. Too high and it locks pH up.
Read the explainer →How pH Affects Your Pool
At pH 8.0, chlorine is nearly useless. At 7.2, your water eats plaster. The 7.4–7.8 target explained.
Read the explainer →LSI: The Water Balance Index
pH alone doesn't tell you if your water is balanced. LSI combines five factors into one number.
Read the explainer →Step-by-step guides
Troubleshooting playbooks for the most common pool problems.
Cloudy or green water
Diagnose your symptoms, then follow the step-by-step fix.
Chlorine levels & problems
What FC, TC, and CC mean, how much to add, and why chlorine drops.
pH & alkalinity
Which to fix first, what chemicals to use, and why the order matters.
Pool algae
Kill green, mustard, and black algae, and stop it from coming back.
Desert pools
Calcium creep, evaporation, hard fill water, and when to drain in hot, dry climates.
Spa & hot tub
Chlorine vs bromine, target ranges, how to shock, and when to change the water.
Pool chemistry FAQ
What should free chlorine be in a pool?
The ideal FC depends on your CYA. At CYA 30, aim for 3–5 ppm. At CYA 50, aim for 5–7 ppm. The rule of thumb: FC should be at least 7.5% of your CYA. See the FC/CYA chart →
Why is my pool cloudy even though chlorine is high?
Usually high CYA is locking up your chlorine, or high pH/alkalinity is causing precipitation. FC looks fine, but effective chlorine is too low. Check CYA first. Diagnose cloudy water →
What is the ideal pool pH?
Keep pH between 7.4 and 7.8, with 7.5–7.6 as the sweet spot. Below 7.2 the water becomes corrosive. Above 7.8, chlorine loses most of its effectiveness. Full pH guide →
How much chlorine should I add?
It depends on your pool volume, current FC, and your CYA-based target. As a rough guide, 1 oz of 12.5% liquid raises FC by ~1 ppm per 1,000 gallons. Use the chlorine dose calculator →
What is LSI?
The Langelier Saturation Index tells you whether your water is balanced, corrosive, or scaling, even when pH looks fine. It combines pH, calcium, alkalinity, and temperature. LSI explained →
How often should I test my pool?
2–3 times per week during swim season, weekly in the off-season. Test in the morning, because UV burns off chlorine throughout the day. Always retest after rain, a pool party, or adding chemicals. Testing schedule →
Where our numbers come from
Every dose, target, and threshold here is based on published standards and other reputable pool chemistry sources (including ANSI/APSP/ICC-11 and CDC guidance), with the formulas and worked examples laid out in full. Written by a pool owner, not a chemist, and upfront about it.
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