CYA level keeps going up

Oct 5, 2015
10
League City, TX
The CYA level in my pool this summer and fall has been high (90-100). I've drained water out and knocked the CYA down but it immediately starts going up again. Did not have this problem last year (in second year of owning house with pool.) The only thing I changed from last year is I'm using chlorine tablets from Sams instead of Costco. Does anyone have any idea what is going on? Thx
 
Welcome to TFP!

Sure, and it's easy. Chlorine Tabs add Cya. Six PPM Cya for every Ten PPM of Free Chlorine that you derive from the typical tablet. As long as you use these as a source of Free Chlorine, you'll be adding Cya to your pool.

Take a moment to check out Pool School, and begin with the ABCs of pool chemistry. From there, read on, and you'll find the things you need to get solid control of your pool. Knowledge is the most important tool in your box, and pool care really becomes easy once you stack some up. Ask all the questions you need too, and read around on the forum. Enjoy your stay here.
 
All Trichlor tabs will increase CYA as indicated. If you saw a difference between last year and this year, then perhaps you used more chlorine this year so increased CYA faster or had less dilution of water this year which have CYA rise faster (i.e. not get diluted down as quickly).
 
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