CYA reference

FC/CYA Chart for Pool Chlorine Planning

Use this FC/CYA chart as planning context for how cyanuric acid changes free chlorine targets. It supports the chlorine, stabilizer, and shock calculators.

Stabilizer Calculator Chlorine Calculator Shock Calculator

Reference chart

Common values for quick planning.

These values are for planning and checking mental math. Use the matching calculator when your pool size, product strength, target range, or current test reading differs.

CYA	Routine FC planning floor	Shock planning target	Calculator to use
20 ppm	2-3 ppm FC	10 ppm FC	Chlorine or shock
30 ppm	2-4 ppm FC	12 ppm FC	Chlorine or shock
40 ppm	3-5 ppm FC	16 ppm FC	Chlorine or shock
50 ppm	4-6 ppm FC	20 ppm FC	Chlorine or shock
60 ppm	5-7 ppm FC	24 ppm FC	Chlorine or shock
80 ppm	6-9 ppm FC	31 ppm FC	Check CYA first

How to use it

Treat chart numbers as a first pass.

Pick the closest pool size, check the matching column, then compare that number with your current test result and product label. If the adjustment is large, use the calculator and add in stages.

Pool volume errors multiply every chemical estimate. If the pool size is uncertain, use the volume calculator before relying on a dosing chart.

Reference FAQ

How to use this chart without overcorrecting.

Use chart values to orient the next step, then rely on fresh test results, calculator inputs, and product labels before adding chemicals.

Is an FC/CYA chart a law or a calculator input?

For this site, it is calculator planning context. Always follow local rules, product labels, and equipment guidance where they apply.

What if CYA is higher than the chart?

Very high CYA can make chlorine planning difficult. Confirm the test, then consider dilution guidance before chasing higher chlorine targets.

Should saltwater pools use the same CYA target?

Saltwater chlorine generator manuals often name their own stabilizer range. Use the equipment manual as the final authority.

Does CYA disappear quickly?

CYA usually does not drop quickly unless water is replaced or diluted. Retest before making a large stabilizer correction.