How much water to drain to reduce CYA?

rccola75

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Jul 21, 2024
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Hi Everyone! I am new to this site. It has been very helpful. I bought a test kit and learning a lot. My pool is ~27500 gallons. Took a CYA measurement and it's ~100ppm. How much water should I drain/refill in order to bring the CYA level to the recommended levels of 50-60ppm for my non salt water pool?
 
Assuming CYA is 100 ppm,

A 40-50% water release will get you to 60-50 ppm CYA

but with such a high CYA value, it is better to set a control diluted CYA measurement of 1:1 pool water and tap water,
then multiply the result by 2

ILSBJ
 
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With CYA of 90+, do the diluted CYA test, #8 (see below) and report that result...


Generally, CYA is 1:1. If your CYA is 150, for example, exchanging 66% of the water will reduce CYA to 50ppm. See "no drain water exchange" here:
 
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