CYA and tri-chlor

[adesalvo]

How much CYA is in a Trichlor puck?

My question concerns my past usage of 3 to 4 pucks a week or 12 - 16 pucks a month. How much CYA am I adding to my pool?

I was hoping to be able to figure this out so that I could set a target for the end of the season. That way, I could set a starting level and prevent a too high CYA level without having to drain.

My pool always opens with a 0 CYA level.

[chem geek]

The answer depends on the size of the pucks. They come in both 8-ounce and 7-ounce and 6-ounce 3" tablets (of varying thicknesses), 3-ounce 1" tablet, and 1-ounce 1/2" tablet. I'll use the 8-ounce 3" tablet for the calculations (that's why I use when I start out with Trichlor to add CYA).

1 puck adds 5.5 ppm FC and 3.3 ppm CYA in 10,000 gallons. This would mean 14 x 3.3 = 46.2 ppm CYA per month in 10,000 gallons. You didn't say the size of your pool so you'll probably need to scale this number down accordingly for a larger pool.

If you have a DE or sand filter that you clean/backwash regularly then this will dilute the pool water so you won't have as much buildup. Same for rain that overflows the pool or for splash-out.

If you let the CYA get higher, you'll have to raise the FC level (see Ben's Best Guess CYA chart) or you'll have to drain/refill periodically to keep the CYA lower or you'll have to use an algaecide (PolyQuat 60) to prevent algae (the latter option being more expensive).

You say you start with 0 ppm CYA after the winter. Do you let your chlorine go to 0 ppm FC over the winter or do you maintain the FC level? If you don't add chlorine, do you find that you have to use a lot of chlorine to clear your pool on opening? Does it have algae upon opening?

Richard

[aylad]

How much CYA is in a Trichlor puck?

I can't give you the chemical makeup like some others can, but I can tell you that in my 29K pool, one puck gives roughly 1 ppm of CYA. I've used trichlor a good bit over the last four pool seasons.....I intentionally run my CYA up to around 80 because I'm in bright, sunny, Louisiana with no shade around the pool, and it usually takes me about 1/2 the season to get it up where I want it. Chemistry is not my thing, but that's my practical experience.

Janet

[adesalvo]

You didn't say the size of your pool so you'll probably need to scale this number down accordingly for a larger pool.

Sorry, 25,000 gallon IG vinyl

If you have a DE or sand filter that you clean/backwash regularly then this will dilute the pool water so you won't have as much buildup. Same for rain that overflows the pool or for splash-out.

I have a unique filter/pump system that uses cloth filter bags. The pool manufacturer is from Europe and is sold in the US as Utopia Pools.

If you let the CYA get higher, you'll have to raise the FC level (see Ben's Best Guess CYA chart) or you'll have to drain/refill periodically to keep the CYA lower or you'll have to use an algaecide (PolyQuat 60) to prevent algae (the latter option being more expensive).

I have been using various algaecides over the years. I am not sure if i should continue this practice. I am leaning towards doing so.

You say you start with 0 ppm CYA after the winter. Do you let your chlorine go to 0 ppm FC over the winter or do you maintain the FC level? If you don't add chlorine, do you find that you have to use a lot of chlorine to clear your pool on opening? Does it have algae upon opening?

My chlorine does go to zero over the winter. I have added 8 gallons of bleach in two days. My Taylor kit is in the mail (Ben's kit never came) and I ran out of DPT tabs at the end of last year. So no real numbers...just pH which has been good.

My pool was opened yesterday and is starting to clear. Mostly dirt...maybe some algea.

Thanks Richard and Janet, this was exactly the info I was looking to get

Tony

[chem geek]

So, 18.5 ppm CYA per month. That's about 120 ppm in a 6-month season so starting at say 20 you end up with 140 if there's no dilution. That's high, but in a vinyl pool you aren't risking plaster degradation that can happen with CYA above 100. At least you clear out the CYA each year over the winter (by letting the FC go to 0). If you don't maintain the higher required FC level, then definitely use an algaecide and PolyQuat 60 is the best. It's not cheap, but it should work to keep away algae.

If you are using pucks because you aren't around (or don't want to) add chlorinating liquid or bleach every day (or don't have a pool cover so you can add it twice a week), then you might consider using Cal-Hypo slow-dissolving tablets instead (not in the same inline feeder as Trichlor -- it's an explosive mixture -- but in a separate feeder, perhaps a floater). Building up CH from the Cal-Hypo isn't as serious and can be diluted once a year.

Richard