Dichlor to raise CYA?

P00LNerd

Bronze Supporter
Apr 20, 2023
264
Pennsylvania
Pool Size
15000
Surface
Vinyl
Chlorine
Liquid Chlorine
Been working to get some pretty out-of-whack chemistry onto the TFP / Pool Math targets, and I'm pretty close now. With conversion to SWG, new target for CYA is 60 - 90, and I'm somewhere right around the minimum there. I say "somewhere around", because I have low confidence in the accuracy of the test method (K2006).

In any case, among the chemicals I had planned to toss is a bottle of dichlor granular. Seems to me, rather than tossing it in the garbage, I might use this to judge my CYA more toward the middle of the range. That'd probably make the garbage men happy, I'm not sure they like disposing of such chemicals.

How much dichlor (Sodium Dichloro-s-Trianzinetrione Hydrated 99%) would one use to nudge CYA up from 60 to 75 ppm? I seem to remember reading somewhere that CYA ppm will move 90% as far as FC, when using dichlor.

The bottle gives zero info on product volume per ppm for a given pool volume, it just says add 5 teaspoons per 1000 gallons, repeating several times until FC = 3 - 5 ppm is achieved.
 
How much dichlor (Sodium Dichloro-s-Trianzinetrione Hydrated 99%) would one use to nudge CYA up from 60 to 75 ppm? I seem to remember reading somewhere that CYA ppm will move 90% as far as FC, when using dichlor.
Pssst...Pool Math.
 
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Pssst...Pool Math.
Doh! I had actually checked under CYA, to see if dichlor was listed, but hadn't thought to check under the Free Clorine tab.

Do you think the 9/10 ratio of CYA rise to FC rise using dichlor sounds about right? If so, I'll just shut off my SWG for a day to give some head room for chlorinating via dichlor, and use that to add the target 15 ppm CYA.

Thanks!
 
Do you think the 9/10 ratio of CYA rise to FC rise using dichlor sounds about right? If so, I'll just shut off my SWG for a day to give some head room for chlorinating via dichlor, and use that to add the target 15 ppm CYA.
Pssst...effects of adding.
 
Pssst...effects of adding.
Okay, will check it out next time I have a chance. Hadn't seen that before.

On the subject of dialing in CYA, I had thought TF test kits or someone sold a CYA reference liquid, but now I'm having trouble finding it. The "disappearing dot" test is so subjective, I'd like a reference to see if I'm judging it right.

Do you know of a source for a known-good reference liquid?
 
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