Pool chemical chart: ideal water levels

Always follow your product’s label directions. Pool and spa chlorine, bromine, shock and algaecides are EPA-registered pesticides: use products labeled for pool or spa use, and don’t swim or soak until levels are within the limit on your product’s label. If this page and a label disagree, the label wins.

Salt pools keep stabilizer at 60–80 ppm. Calcium should be 200–400 ppm for plaster, or 150–250 ppm for vinyl and above-ground pools. Free chlorine rises with your stabilizer. The chart below lists each level with its source. Enter your own test in the calculator above to see which numbers are off and what to add first.

The chart (with sources)

"Target" is where we suggest you keep your pool. "Acceptable" is the wider range published by the CDC, the Model Aquatic Health Code (MAHC), APSP-11 (as published by PHTA), or Taylor. Water outside the target but inside the acceptable range still meets these published ranges; it is only less comfortable or harder to keep stable. Every range, and why we chose it, is on our methodology page.

Pool chemistry chart

Parameter	Target	Acceptable
Free chlorine (FC)	depends on CYA (see chlorine levels)	at least 1 ppm; 2 ppm with CYA; no swimming above 10 ppm
pH	7.4–7.6	7.2–7.8
Total alkalinity (TA)	80–120 ppm (60–90 for salt and liquid chlorine pools with rising pH)	60–180 ppm
Calcium hardness (CH)	plaster 200–400 ppm; vinyl, fiberglass, and above-ground 150–250 ppm	150–1,000 ppm
Stabilizer (CYA)	chlorine 30–50 ppm; salt 60–80 ppm	up to about 90 ppm
Salt (salt water pools)	about 3,200 ppm or your cell manual	cell manual range
Combined chlorine (CC)	0 ppm	below 0.5 ppm
LSI (water balance)	−0.3 to +0.3	up to +0.5

Sources: CDC, MAHC 2024 Annex, PHTA / ANSI-APSP-11 (via PHTA documents), Taylor. Target ranges are our choice inside the acceptable ranges; see methodology.

Download this data (CSV) · License: CC BY 4.0

Test free chlorine and pH often. Total alkalinity (TA), calcium, and stabilizer change slowly, so testing them weekly to monthly is usually enough. Correct in this order: chlorine first if it is below the minimum, then alkalinity, then pH, then calcium and stabilizer. The pool chemical calculator builds that plan for you.

Free chlorine

Free chlorine (FC) is the sanitizer that kills germs and algae. There is no single right number: stabilizer holds part of the chlorine in reserve, so the more CYA in the water, the more FC you need. The CDC's model code (2024 Annex) explains the principle. Our calculator sets the minimum at about 7.5% of CYA (5% for salt cells), and never below 2 ppm when CYA is present.

Most pool chlorine labels say not to swim above 4 ppm. At 50 ppm CYA and above, the minimum alone reaches or passes that limit, which is one more reason to keep stabilizer at 30–40 ppm in chlorine pools. Combined chlorine (CC), which is total chlorine minus free chlorine, should be close to 0. At 0.5 ppm or more, shock the pool as your product's label directs. The full table with minimums is on pool chlorine levels. The difference between the two test numbers is explained on free vs total chlorine, and product choice on types of pool chlorine.

pH

Keep pH at 7.4–7.6; 7.2–7.8 is acceptable. pH controls how much of your chlorine is in its active form: the MAHC Annex gives roughly 70% at pH 7.0, about 50% at 7.5, and about 20% at 8.0. Low pH stings eyes and corrodes equipment. High pH weakens chlorine and helps scale form. In most pools, pH drifts up over time. See how to lower pH or how to raise pH. Background is on pool pH levels.

Total alkalinity

Total alkalinity (TA) is the buffer that keeps pH from jumping around. Aim for 80–120 ppm. Pools with salt cells or liquid chlorine, where pH keeps rising, often do better at 60–90 ppm, because lower TA slows the rise. Low TA lets pH swing. High TA makes pH climb, so you need acid every few days. See raising alkalinity, lowering alkalinity, and alkalinity levels.

Calcium hardness

Calcium hardness (CH) matters mostly for plaster, pebble, and tile grout. Water that is low in calcium slowly dissolves them. Water high in calcium leaves scale. We suggest 200–400 ppm for plaster pools and 150–250 ppm for vinyl, fiberglass, and above-ground pools. APSP-11 accepts 150–1,000 ppm. CH only goes down with fresh water. The LSI calculator shows whether your mix of pH, TA, calcium, and temperature leans toward etching or scaling. More on calcium hardness and lowering it.

Stabilizer (CYA)

Cyanuric acid (CYA) protects chlorine from sunlight in outdoor pools. Aim for 30–50 ppm with liquid chlorine, bleach, or tablets, and 60–80 ppm with a salt cell if your cell's manual allows it. Hot tubs and indoor pools need none (CDC). Too much CYA raises the free chlorine you need, and the only way to lower CYA is to replace water. Baking soda, acid, and shock don't change it; only stabilizer, trichlor, and dichlor add it. Read what cyanuric acid is and how to lower CYA.

Salt

Only salt water pools need salt. Use your chlorinator's manual: Hayward's AquaRite manual gives 2,700–3,400 ppm with 3,200 ppm ideal, and Pentair's IntelliChlor quick start guide says 3,200–3,400 ppm. Salt leaves only with water, so you need to add salt after backwashing, splash-out, or rain overflow, not after evaporation. See pool salt level and salt water pool care. Thinking about switching? Compare salt water vs chlorine and read about converting a pool to salt.

What should a salt chlorinator be set at?

There is no single right number. The percent on the control box is the share of pump run time the cell spends making chlorine, so the right setting depends on your pool size, pump hours, sun, water temperature, and stabilizer. Start from your cell manual's suggestion, test FC daily for a week, and change the setting in small steps until FC holds in the target range above. If FC stays low at a high setting, check the salt level and clean the cell before turning it up further.

Printable cheat sheet

A short version to post near your pool equipment:

• FC: about 7.5% of CYA, at least 2 ppm with CYA (3–5 ppm at CYA 40). Swim only at or below the limit on your chlorine label (often 4 ppm); never above 10 ppm.
• pH: 7.4–7.6 (7.2–7.8 OK).
• TA: 80–120 ppm (60–90 for salt pools).
• CH: plaster 200–400 ppm; vinyl, fiberglass, and above-ground 150–250 ppm.
• CYA: 30–50 ppm; salt pools 60–80 ppm; hot tubs none.
• Salt: about 3,200 ppm, or per your cell manual.
• CC: under 0.5 ppm; if higher, shock (follow the label).
• Order: chlorine (if low) → alkalinity → pH → calcium → stabilizer. One product at a time, pump running, never mix chemicals.

For a hot tub, the numbers are different (chlorine 3–4 ppm or bromine 4–6 ppm, no stabilizer, 104 °F maximum): see hot tub water care and the hot tub chemical calculator. The full hot tub table is on the hot tub chemical chart.

All chemistry guides

Every guide in this section is listed below. The quickest route by problem: if pH or alkalinity is out of range, use the four raise and lower guides above. If chlorine won't hold or reads strangely, start with chlorine levels and free vs total chlorine. If you can't explain your chlorine demand, check phosphates. To check everything at once from one test, use the chemical calculator.

FAQ

How to balance pool water chemistry?

Test free chlorine, pH, total alkalinity, and stabilizer (plus calcium and salt when relevant). Then correct one thing at a time in this order: chlorine if it is below the minimum for your stabilizer, then alkalinity, pH, calcium, and stabilizer. Let the pump run about 30 minutes between products and retest before the next big step.

What should pool water chemical levels be?

pH 7.4–7.6, total alkalinity 80–120 ppm, calcium 200–400 ppm for plaster or 150–250 ppm for vinyl and above-ground pools, stabilizer 30–50 ppm (60–80 for salt), salt about 3,200 ppm for salt pools, combined chlorine under 0.5 ppm, and free chlorine about 7.5% of your stabilizer level: 3–5 ppm at CYA 40.

How to test pool water chemistry?

Test strips are quick for a daily check of chlorine and pH. A drop-based kit, especially one with a FAS-DPD chlorine test, is more precise for chlorine, alkalinity, calcium, and stabilizer. The CDC advises home pool owners to test chlorine and pH at least twice a day, and more often with heavy use. Take the sample from elbow depth, away from return jets.

Sources

• CDC, Home pool and hot tub water treatment and testing: cdc.gov
• CDC, Model Aquatic Health Code 2024, Annex: cdc.gov (PDF)
• ANSI blog, ANSI/APSP-11 water quality in public pools and spas: blog.ansi.org
• Taylor Technologies, K-1005 instruction manual: PDF
• Hayward, AquaRite manual: PDF
• Pentair, IntelliChlor SCG Quick Start Guide and Tips: PDF