What should CYA and chlorine be in a salt water pool?
Salt water pools usually run their stabilizer higher, around 60 to 80 ppm. At 70 ppm CYA, keep free chlorine at least 3.5 ppm (5% of CYA, the salt-generator convention), in a daily range of 3.5–6.5 ppm; the shock level is 28 ppm.
How to work it out
- In short: the more stabilizer in the water, the more chlorine it needs, so each level is a share of your CYA.
- Minimum: 70 ppm CYA × 5% = 3.5 → 3.5 ppm (rounded to the nearest whole ppm, never below 1 ppm)
- Shock (SLAM): 70 × 40% = 28 ppm
- Public-pool floor: the larger of 2 ppm and 70 ÷ 45 = 1.56 → 2 ppm
A salt chlorine generator makes chlorine a little at a time whenever the pump runs. That steady trickle is why salt pools can run a lower chlorine-to-CYA ratio than pools dosed by hand, and why they usually carry more stabilizer: the cell can’t outrun a summer sun on low CYA.
Adjust for your project
- A comfortable daily range
- 3.5–6.5 ppm
- Shock (SLAM) level for algae
- 28 ppm
- Public-pool floor (MAHC 45:1 ratio, 2 ppm minimum)
- 2 ppm
- Salt generators make chlorine all day in small amounts, so the convention allows a lower ratio (5% of CYA) — and most salt pools run 60–80 ppm of CYA so the sun doesn’t outpace the cell.
Salt water pool: chlorine by stabilizer level
| CYA | Keep free chlorine at least | A comfortable daily range | Shock (SLAM) level for algae |
|---|---|---|---|
| 40 ppm | 2 ppm | 2–4 ppm | 16 ppm |
| 50 ppm | 2.5 ppm | 2.5–4.5 ppm | 20 ppm |
| 60 ppm | 3 ppm | 3–5.5 ppm | 24 ppm |
| 70 ppm | 3.5 ppm | 3.5–6.5 ppm | 28 ppm |
| 80 ppm | 4 ppm | 4–7 ppm | 32 ppm |
| 90 ppm | 4.5 ppm | 4.5–8 ppm | 36 ppm |
Why salt pools run higher CYA
At 30 ppm of stabilizer, midday sun can destroy chlorine faster than a typical cell makes it, so the cell has to run longer and wears out sooner. At 60–80 ppm, more of the chlorine is held in the sun-resistant bound form, and a cell set to a modest output keeps up. The trade-off is that you then need more free chlorine — but the generator supplies it continuously instead of in once-a-day spikes.
- Minimum. The Trouble Free Pool convention for salt pools is free chlorine of at least 5% of CYA: 3.5 ppm at 70, 4 ppm at 80. That is a hobbyist rule, not a code; the CDC minimum with stabilizer is 2 ppm.
- Check your cell manual. Manufacturers list their own recommended CYA and salt ranges for their cells; where the manual and this page differ, follow the manual.
- Shock still needs a lot. At 70 ppm CYA the shock (SLAM) level is 28 ppm — usually done with liquid chlorine, because a cell can’t raise chlorine that fast.
- Don’t overshoot CYA. Stabilizer only leaves with water. Above 90 ppm, see how much water to drain to lower CYA.
To get CYA up to the range, use how much stabilizer for a 20,000 gallon pool as a worked example; for the salt itself, how much salt for a 15,000 gallon pool.
Different size? Use the full Chlorine & Stabilizer (FC/CYA) Calculator.
What you’ll need
- FAS-DPD drop test kit (chlorine, pH, TA, CH, CYA)Mid-range price
A drop-count kit reads free chlorine to 0.5 ppm (or 0.2 ppm), plus pH, alkalinity, calcium and stabilizer. Every dose on this site starts from a test, so this is the one thing worth buying first.
See options on Amazon (opens in a new tab) - Salt test stripsBudget price
Check salt independently of the salt cell’s own reading, which drifts as the cell ages.
See options on Amazon (opens in a new tab) - Stabilizer / conditioner (cyanuric acid)Budget price
Shields chlorine from sunlight. Dissolves slowly — follow the label (many say a skimmer or a sock), and don’t backwash for a few days.
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Frequently asked questions
What should chlorine be in a salt pool with 80 ppm CYA?
At least 4 ppm, with a shock level of 32 ppm.
What chlorine level does a salt pool need at 50 ppm CYA?
At least 2.5 ppm by the 5% convention (the CDC floor with stabilizer is 2 ppm); shock level 20 ppm.
Sources
- Trouble Free Pool (hobbyist forum wiki) — CYA/chlorine relationship (opens in a new tab) — A widely used hobbyist convention, not an official standard: minimum FC 7.5% of CYA, SLAM (shock) level 40% of CYA, salt-water pools 5%.
- CDC Healthy Swimming — Home pool and hot tub water treatment and testing (opens in a new tab) — pH 7.0–7.8; free chlorine at least 1 ppm in pools (2 ppm with cyanuric acid) and 3 ppm in hot tubs; no CYA in hot tubs; test twice a day.
- CDC — Model Aquatic Health Code, 5th edition (2024), code (opens in a new tab) — Free chlorine minimum 1.0 ppm (2.0 with CYA, 3.0 in spas); pH 7.0–7.8; CYA at or below 90 ppm; CYA:FC above 45:1 is an imminent hazard; TA 60–180 ppm; turnover tables.
- CDC — Model Aquatic Health Code, 5th edition (2024), annex (opens in a new tab) — CYA reduces chlorine’s effectiveness; correcting total alkalinity for CYA by subtracting CYA ÷ 3.
- Trouble Free Pool — The free chlorine and cyanuric acid relationship (chart) (opens in a new tab) — The same convention as a chart, with a separate table for salt-water pools.
- Michigan Administrative Code R 325.2194 — swimming pool chemical levels (opens in a new tab) — An example of a state rule that raises the chlorine minimum as CYA rises: 2.0 mg/L at 20–40 ppm CYA (pH 7.2–7.5), plus 0.5 mg/L for each further 20 ppm, CYA no more than 80.