Is it possible that Leslie's pool tablets don't have CYA?

[paulzimmer]

I used tablets for years. After battling algae problems, I found this wonderful site and learned about CYA. I drained my 27K gallon pool and restarted spring 2019. All went well last summer. At the start of this season, I checked CYA and it was low. Since I was out of CYA proper, I thought, "what the heck, I'll just use tablets until the CYA level is where I want it." Used 6 pucks. No change in CYA. 8 more. No change. CYA is something like 30-35 (hard to tell when the black dot disappears).

I don't think its a CYA measurement problem, because chlorine consumption (with new, just bought chlorine) us more than 2x what it was this time last year.

Is it possible that those tablets (from Leslies) don't have CYA? It doesn't list CYA on the label (see attached).

Thanks SO much,
Paul Zimmer

 

[magiteck]

Trichlor, which is the active ingredient listed on your container, is also chemically known as Trichloroisocyanuric acid.

It most definitely contains CYA which is also why they boast “protected from sunlight” on the container.

To convert chlorine gas into a solid it has to be bound to something. Options are CYA (Dichlor and trichlor) or calcium (cal hypo).

 

[magiteck]

Also ... in a 27,000 gallon pool, 14 8oz trichlor pucks would add approx 17ppm of CYA.

You’re also going to have some degradation in the hot Cali sun, so you may have only gotten a net increase of 10ppm or so, which isn’t the easiest to measure.

 

[paulzimmer]

" Also ... in a 27,000 gallon pool, 14 8oz trichlor pucks would add approx 17ppm of CYA. " Yeah, I was expecting about 1-1/4 ppm per puck, wo that sounds about right.

So, the CYA part would degrade as well? It is a pretty old tub of pucks.

Shame, I was hoping I'd found pucks without CYA, which would allow me to use the feeder again.

 

[magiteck]

" Also ... in a 27,000 gallon pool, 14 8oz trichlor pucks would add approx 17ppm of CYA. " Yeah, I was expecting about 1-1/4 ppm per puck, wo that sounds about right.

So, the CYA part would degrade as well? It is a pretty old tub of pucks.

Shame, I was hoping I'd found pucks without CYA, which would allow me to use the feeder again.

Pucks without CYA or other harmful additives would be kind of like the holy grail, and I’m sure the TFP crowd would jump on them. Unfortunately, they don’t exist, and as such liquid chlorine or a SWCG remains the best recommendation. Some on the forum have also invested in an automatic feeder for liquid chlorine.

CYA in the pucks themselves doesn’t necessarily degrade, but it does slowly degrade in the water - especially hotter water from what I’ve read. It doesn’t degrade as fast as regular use of pucks will continue to add it, though- just enough that it doesn’t necessarily last “forever” in the water - hence the recommendation to test CYA at least monthly or so, even if you know you haven’t added any.

Your CYA is low enough now that you can certainly get away with floating some pucks for a long weekend or whatever, but stick with liquid chlorine for daily maintenance to stay out of trouble.

 

[Chasarms]

I lose about 4-5 ppm per month of CYA or slightly more. My pool is in direct sun all day and has no deep end. It reaches water temps of 88-90 for extended periods.