MyPoolLabPool Chemistry & Volume

Cyanuric Acid (CYA / Stabilizer) Calculator

Calculate dry and liquid stabilizer dosing to protect chlorine from UV breakdown, or determine the required drain percentage for chlorine lock.

Volume Unit
Target Presets:
gal

Waterline capacity

ppm

Tested with turbidity view tube

ppm

30–50 standard | 60–80 salt

Stabilizer Action Plan

Add 3.7 lbs (1.7 kg) of granular stabilizer using the sock-in-skimmer method to protect chlorine from sunlight.

Dry Granular Cyanuric Acid
3.7 lbs (1.7 kg)

≈ 59 dry ounces. Dissolves slowly.

Liquid Pool Conditioner Option
144 fl oz (4259 mL)

Instant-acting liquid suspension.

Pro Tip: Put dry stabilizer inside an old sock and hang it in front of the return jet. Do not pour directly into the skimmer or pool floor, as it takes 24–48 hours to dissolve.
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Why Stabilizer Levels Must Be Controlled

In outdoor swimming pools, Cyanuric Acid is essential. Without stabilizer, sunlight converts free chlorine into inactive chloride ions within 2 hours. However, each increase in CYA binds chlorine tighter, reducing the proportion of active hypochlorous acid (HOCl).

When CYA rises above 100 ppm (caused by continual use of trichlor tabs or dichlor shock), the pool enters Chlorine Lock. At this point, algae can spread even with elevated total chlorine readings because insufficient free active chlorine is available.

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Frequently Asked Questions

What is Cyanuric Acid (CYA) and why does my pool need it?

Cyanuric Acid (pool stabilizer or conditioner) acts as sunscreen for chlorine. Without stabilizer, ultraviolet rays from sunlight degrade up to 90% of free chlorine within two hours. CYA binds loosely with hypochlorous acid to protect it from UV breakdown.

What is the ideal CYA level for swimming pools?

For traditional chlorine pools (using liquid chlorine or pucks), 30 to 50 ppm is ideal. For saltwater generator (SWG) pools, 60 to 80 ppm is recommended to protect the cell from running at maximum capacity in hot summer months.

How do I add dry stabilizer without clogging my filter?

Never dump granular CYA directly into the skimmer or pool floor (it takes days to dissolve and can cake in the filter). Put the calculated amount into an old tube sock or skimmer sock, tie the top, and suspend it in front of a return jet or hang it inside the skimmer basket. Squeeze the sock occasionally until dissolved.

How do I lower high Cyanuric Acid (Chlorine Lock)?

Cyanuric acid does not evaporate or break down with shock. The only proven, reliable method to lower CYA is draining a portion of your pool water and refilling with fresh water.