06/02/2026
Your chlorine tabs may be causing your green pool.
Most 3-inch chlorine tabs are trichlor, which means they add chlorine and CYA/stabilizer every time they dissolve.
CYA is helpful because it protects chlorine from the Texas sun…
…but too much CYA “over-protects” the chlorine and makes it less effective.
That’s why your pool can technically show chlorine on a test strip and still turn cloudy or green.
A good target for most backyard pools is around 40 ppm CYA.
Pool chemistry expert Bob Lowry’s rule is simple:
Your free chlorine should be at least 7.5% of your CYA level.
So if your CYA is 40, your free chlorine should be at least about 3 ppm.
But if your CYA climbs to 100, now you need at least 7.5 ppm free chlorine just to keep up.
That’s why relying on tabs all season can create problems.
TL;DR: Tabs are useful, but they quietly raise CYA. Too much CYA makes chlorine less effective. Keep CYA around 40 and test it regularly.
Not sure where your CYA is? Message us “CYA” and we’ll help.
New Braunfels Pool Professionals
Zero-Stress Pool Care™
TexasPools PoolTips CYA ChlorineTabs PoolChemistry
