Free tool · Rate my pool

Pool health check

Grade your water and equipment in 2 minutes, then get the exact fixes in the right order.

How these numbers are worked out, and the sources behind them: see our methodology. Updated 2026-10-21.

What a pool health check covers

Water chemistry: sanitizer, pH, alkalinity, calcium, stabilizer and salt, plus water balance (LSI).
Circulation:pump runtime, baskets and water level. If water doesn't move through the filter, chemistry can't keep up.
Filtration: filter pressure and how long since the last clean.
Surfaces: algae, scale and clarity, the visible signs that something above has slipped.

Track readings over time with water chemistry tracking in Skimmer.

Ideal ranges we grade against

Green, amber and red bands for each reading
Reading	Good	Borderline	Fix now
Free chlorine	7.5% to 11.5% of CYA (3 to 5 ppm at 40)	Below 7.5% of CYA	Under about 5% of CYA
Combined chlorine	0 to 0.5 ppm	0.5 to 1 ppm	Over 1 ppm
pH	7.3 to 7.7	7.0 to 8.0	Outside 7.0 to 8.0
Total alkalinity	60 to 120 ppm	40 to 150 ppm	Outside 40 to 150
Calcium hardness	200 to 400 ppm	150 to 500 ppm	Outside 150 to 500
Cyanuric acid	30 to 50 ppm (60 to 80 salt)	20 to 80 ppm	Outside 20 to 80
Salt	2,700 to 3,400 ppm	2,400 to 3,800 ppm	Outside 2,400 to 3,800

Want them on paper? Print the ideal pool chemistry cheat sheet.

How often to check

Two or three times a week: free chlorine and pH.
Weekly: full water test, baskets, water level and filter pressure.
Monthly: calcium, stabilizer and salt; clean the filter if pressure is up.
Seasonally: a full equipment check at opening, mid-season and closing.

More: how often to test pool water, testing without a smart monitor and the best pool test kits.

Health check vs a pro inspection

This check catches the things an owner can see and test. Call a pro, or book a full inspection, if the pool loses more than about a quarter inch of water a day beyond evaporation, the pump hums but doesn't move water, the heater or salt cell throws errors, there are cracks or loose tiles, or you're buying a house with a pool. See the pool inspection checklist before buying.

How to use this calculator

1
Test your water
Use a kit or strips for free chlorine, pH, alkalinity, calcium and stabilizer (plus salt or bromine if you use them).
2
Enter numbers or tap strip colors
Leave any field blank to skip it. Add your pool's gallons to get exact doses.
3
Answer the equipment questions
Clarity, algae, filter pressure, pump runtime, baskets, filter cleaning, scale and water level.
4
Read your score
Water counts 70% and equipment 30%, combined into a score out of 100 and a letter grade.
5
Work through the fix plan
Alkalinity before pH, chlorine last, SLAM first if there is algae. Retest and check again.

More free tools

Pool Chemical Calculator

Every dose from one test, with your own products.

Pool Chlorine Calculator

Daily, shock and SLAM doses.

Pool pH Calculator

Muriatic acid, soda ash or borax doses.

LSI Calculator

Check whether the water will etch or scale.

Which Calculator Do I Need?

Two questions to the right tool.

More pool calculators →

Frequently asked

Questions about the pool health check

How do I check my pool's health?

Test the water (chlorine, pH, alkalinity, calcium, stabilizer), then look at the pool itself: can you see the drain, is there algae, is filter pressure up, are the baskets full, is the water level right. This check grades both and tells you what to fix first.

How is the Pool Health Score calculated?

Each reading is graded good, borderline or out of range against standard targets, and each equipment answer the same way. Water counts 70% and equipment 30% of the score out of 100. Free chlorine is graded against your CYA (minimum about 7.5% of CYA), because a fixed chlorine target is wrong for a stabilized pool.

What does a high filter pressure mean?

Pressure 8 to 10 psi above the reading right after a clean means the filter is full of dirt. Backwash a sand or DE filter, or hose off a cartridge. Pressure that stays high after cleaning can mean a clogged return or a closed valve.

Why is my pool cloudy if the chemistry is fine?

Usually the filter: it is dirty, too small or not running long enough. Check filter pressure and pump runtime. High calcium with high pH, and early algae that hasn't turned green yet, also cloud water.

Can I check pool water with test strips?

Yes. Switch to Strip colors and tap the swatch closest to each pad. Strips are fine for a weekly check; use a drop test kit for CYA and calcium, which strips read poorly.

How often should I do a pool health check?

Test chlorine and pH two or three times a week in summer, do a full check weekly, test calcium and stabilizer monthly, and do a full equipment check at opening, mid-season and closing.

Do I need to enter every number?

No. Leave any field blank and it's skipped. The more you enter, the more complete the grade.

Is a good score a guarantee my water is safe?

No. This is a diagnostic estimate from the numbers you enter. It can't catch a bad test reading or anything you didn't enter, and it doesn't replace a full test or professional judgment.