It doesn't make sence that the people who make them, wouldn't also make them without cya. They must know that after a while their customers will have too much cya. filix.

Unstabilzed dry chlorine (if it existed) would disintegrate/be hard to handle and might go BOOM.

There is cal-hypo which is calcium hypochlorite, but that adds calcium.

I think you believe that the chlorine products have CYA added to them, but that is not the case. The various chlorine products are chemical compounds (molecules), not mixtures of chlorine with CYA or chlorine with calcium. Look at the chemical structure of Trichlor, Dichlor and Cal-Hypo. The CYA and calcium are part of the molecule itself. Compare that to sodium hypochlorite. Believe me, if it were possible to create a slow-dissolving tablet with chlorine that didn't increase CYA nor CH, it would have been invented by now. Unfortunately, the chemistry limits what is possible.

Probably the closest product that could do this would be lithium hypochlorite since it is in solid (powder/granular) form so could, in theory, be compressed into tablets, though likely would need some sort of binders just like Cal-Hypo tabs and they tend to fall apart too quickly and leave a gummy mess. Lithium hypochlorite is also VERY expensive -- over 5 times the price of chlorinating liquid, bleach or Cal-Hypo. There is also magnesium hypochlorite but it only comes in a form that has magnesium hydroxide so is very basic/alkaline.

Good point, I stand corrected

Solved the problem. Just take one part sodium hypochlorite and add one part liquid nitrogen dewar and there you go...Solid non-stabalized chlorine.

Could go boom? People flying out of the pool? Not good. Chem Geek Thanks for the chemistry lesson. I always enjoy reading your posts. Thats just what I thought, that they added it. Now I get it! They can't make! filix.

I am no chemical expert, but is this product just pure chlorine with nothing that increases CYA? The site also has the MSDS for the chemical experts.

http://www.usabluebook.com/p-266090-hm- ... -size.aspx

That's calcium hypochlorite that is usually around 35% or so calcium.....another no-no if it gets too high. They are also usually not very acceptable in pools as they dissolve too quickly.

There are tabs made with Dimethyl Hydantoin and 5-ethyl-5-methylhydantoin, which I think are used in some swimming pools outside of the US. Some bromine tabs contain 1,3-Dichloro-5,5-Dimethyl Hydantoin and 1,3-Dichloro-5-ethyl-5-methylhydantoin, such as Bio guard bromo brix spa brominating briquettes, Kem tek spa kem bromi-buoy,Bioguard brombrix pool brominating briquettes, and Dantobrom.

The only (100 %) 1,3-Dichloro-5,5-Dimethyl Hydantoin pool product I could find was Swimfree chlorinator for swimming pools, which no longer has an active registration.

http://www.pesticideinfo.org/Detail_Pro ... _NR=006836

http://www.pesticideinfo.org/Detail_Pro ... _NR=006836

http://www.pesticideinfo.org/Detail_Pro ... _NR=007616

http://www.pesticideinfo.org/Detail_Pro ... _NR=006836

I'm not sure why 1,3-Dichloro-5,5-Dimethyl Hydantoin and 1,3-Dichloro-5-ethyl-5-methylhydantoin are not used in the US except for in bromine tabs. The hydantoin does build up and reduce chlorine or bromine's effectiveness, but it's not clear how much.

Other than bromine tabs, the only US products that I could find that use hydantoin based chlorine tabs are the tabs used in toilet bowl bleach tablet products, such as X-14 Automatic Toilet Bowl Cleaner.

has anyone ever tried using these x14 tabs in your pools?

I wouldn't use those. They might contain some unknown problem chemical. Even if they didn't contain any other chemicals than what are listed, the dimethylhydantoin can be a problem in its own right.

Liquid chlorine (sodium hypochlorite) is really the best choice in most cases.