# Thread: How Much CYA is in One 3 inch Tab???

1. ## How Much CYA is in One 3 inch Tab???

I assume this is the best sub-forum to ask these questions:

I have a lot of 3 inch trichlor tabs. They say they are "90% available stabilized chlorine, 99% Trichlor-S-Triazinetrione" on the label.

I also have high CYA at about 85. Boo....

So, once I get the CYA back down to where it should be (Target 30-40), I was wondering how I can calculate how many 3" tabs it would take to raise the CYA by 1 PPM for a 25,000 gal pool (my size pool in this example).

I would also like to know how much CL2 is in one of those pesky tabs. It would be nice to equate one tab is equal to a certain number of ounces of 8.25% Bleach or certain number of ounces by volume of 68% Cal-hypo, etc.....

I travel on biz occasionally, and I think if I can get my CYA fixed (30-40).....I hope it won't be a big deal to leave a couple of these 3 in tabs in a pool floater while gone for a week. Right?
I say this becuase I noticed that when I closed the pool last year and re-opened it, my CYA went from 50 to 0. So it seems "winter" cleanses the pool of CYA, just like a drain out.

On simialr topic, I wonder what the shelf life of these 3 inch tabs is? Can they be stored in cold weather outside in a pool deck box over winter, or must they be stored in a garage where temps would likely stay about 55 F all winter.

2. ## Re: How Much CYA is in One 3 inch Tab???

As long as they are stored dry, they will last indefinitely. If they are TriChlor, you will get 6 PPM Cya for every 10 PPM FC derived from the pucks.

3. ## Re: How Much CYA is in One 3 inch Tab???

PoolMath my friend, PoolMath does it all.

So if we assume your 3" puck weighs 8oz (weight varies a bit with manufacturer) and your pool is 25k gallons, then one puck-

Raises your FC by 2.2ppm and your CYA by 1.3ppm

2.2ppm FC in your pool is equivalent to 81oz (2 quarts and 2 cups) of 8.25% bleach.

Just use PoolMath and all mysteries will be revealed.....

4. ## Re: How Much CYA is in One 3 inch Tab???

Thanks everyone....As an Electrical Engineer, I dig Pool Math. If the Pool Calculator was updated to include this info, that would be awesome.

The reason I am interested in pucks (or slow release CL) is for when I travel. Maybe SWG is in my future???

I'll see if I can weigh one of those 3 inch pucks, and 8 oz sounds about right. The CYA content per puck is a lot more than I anticipated. Wow.

That leads me to think "why the heck in the first place do the put CYA in the pucks? Think about it. If I start my pool out at CYA = 40 at spring opening...and I do the floater thing at lets say 2-3 pucks per week, well you can see that in no time flat we are hosed on too much CYA.

I found a non-stabilized solid CL for floaters and skimmers last year. But it was awful. I don't know what else was in in (i.e. Calcium???) They were tubular, approx 4" L x 1" diameter, wrapped in heavy clear plastic, and only the end of each tube was exposed to the CL. The chlorine broke down in to little chips in the skimmer basket...so when you cleaned out leaves you had fifty little chunks of CL in the bottom of the basket, each the size of a dime or smaller. Bad product.

5. ## Re: How Much CYA is in One 3 inch Tab???

Check out the bottom of Pool Math - effects of adding chemicals. I think you'll dig it.

6. ## Re: How Much CYA is in One 3 inch Tab???

Originally Posted by mmcwhorter10
Thanks everyone....As an Electrical Engineer, I dig Pool Math. If the Pool Calculator was updated to include this info, that would be awesome.

The reason I am interested in pucks (or slow release CL) is for when I travel. Maybe SWG is in my future???

I'll see if I can weigh one of those 3 inch pucks, and 8 oz sounds about right. The CYA content per puck is a lot more than I anticipated. Wow.

That leads me to think "why the heck in the first place do the put CYA in the pucks? Think about it. If I start my pool out at CYA = 40 at spring opening...and I do the floater thing at lets say 2-3 pucks per week, well you can see that in no time flat we are hosed on too much CYA.

I found a non-stabilized solid CL for floaters and skimmers last year. But it was awful. I don't know what else was in in (i.e. Calcium???) They were tubular, approx 4" L x 1" diameter, wrapped in heavy clear plastic, and only the end of each tube was exposed to the CL. The chlorine broke down in to little chips in the skimmer basket...so when you cleaned out leaves you had fifty little chunks of CL in the bottom of the basket, each the size of a dime or smaller. Bad product.
We do tend to use language interchangeably that is not technically, 100% accurate. "They" do not "add CYA" to their solid chlorine products. The solid chlorine products are chlorinated triazinetrione sodium salts. When you add those compounds to water, they become one of six different chemical compounds we call chlorinated isocyanurates. When you add cyanuric acid to chlorinated pool water, the cyanuric acid gets converted to those chlorinated isocyanurates. SO it's not like "they" mix CYA and chlorine together in a puck, it's really it's own distinct solid chemical that, once added to water, forms an equilibrium between hypochlorous acid and one of the six chlorinated isocyanurates.

But, be glad in some sense that these compounds exist in the first place. You see, chlorine is highly reactive and cannot be handled on it's own without proper hazardous materials protection. Also, many hypochlorite compounds are extremely reactive and can not be handled in their pure forms. Sodium hypochlorite (bleach) only exists in a reasonably stable form as a liquid mixture of water and sodium hypochlorite. It is still very reactive which is why the high grade stuff (>12%) breaks down so quickly. Potassium hypochlorite is similar. Hypochlorites of lithium and calcium are solids but they are also very reactive as well. A 1-lb bag of 73% cal-hypo contains a significant amount of chlorine which is a very powerful oxidizer. Left on it's own, it can react violently with organics and self-ignite under certain circumstances. So, while chlorine is a wonderfully powerful disinfectant, sanitizer and oxidizer, it is by no means easy to work with and we are stuck with having to work with its various stabilized solid forms.

As for your specific situation (traveling engineer), you should consider either a salt-water chlorine generator or a liquid chlorine Stenner pump to automate chlorine additions to your pool. I believe it would be a big benefit to your lifestyle and allow you to leave your pool for extended periods without having to worry about how to chlorinate without ruining your water.

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