Keeping CYA within range

Jetomaticace

New member
Oct 17, 2023
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I’m a first time pool owner of an 18,000 gallon in ground beauty. At the time CYA was off the chart and black algae was getting a foothold so we drained and acid washed the pool and upon refilling CYA came in at 5.0 ppm. To raise the CYA level I purchased Clorox 3” chlorinating tabs as I understood them to be appx 60 % chlorine and 35% cyanuric acid. At home now and reading the label it says the tablets each contain 94% trichloto-s-triazinetrione. Does this mean there is no CYA in this product? Thank you for your consideration I really hope to have a “trouble free pool” using primarily liquid chlorine.
 
Hey Jeto and belated Welcome !!

Each 8 oz puck will raise your CYA 2 ppm.

The irony is if it was your sole source of chlorine, the CYA would quickly spiral out of control but you need the CYA to be 30 quickly and it will take too long getting there from 5.

With no/little CYA, the FC will burn off quickly and you'd need to check it several times a day.

Use 'trichlor' in PoolMath or to see all the other chemicals and what they do.
 
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tablets each contain 94% trichloto-s-triazinetrione
A very simple explanation that leaves a lot of technical stuff out is: Trichlor is a molecule that breaks down to 2 molecules of chlorine and 1 molecule of CYA. I'm sure some of the chemists on the forum are cringing right now. As such every 2 ppm FC you get from tablets, 1 ppm CYA is also added to the water. There's some rounding to those numbers, but it's pretty close to that.

As newdude said, you really need CYA in the water quickly and tablets won't do that. Also those tablets are only 94% pure, the remaining 6% is stuff you don't really want in your water. Probably some mix of clarifier, metal algaecide, etc. I wouldn't use them. Also you're going to want to be able to test your own water, that 5 ppm reading on CYA screams pool store or worse. Having one of our recommended test kits is really key to moving towards a truly Trouble Free Pool. Test Kits Compared

And welcome to TFP! We can certainly help you never have to deal with anything like what you've been through again. You got this :goodjob:
 
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