CYA in Trichlor?

[jhm]

I know trichlor is stabilized, but does it actually contain cya? It doesn't list it as an ingredient, and if not, why does it contribute to higher cya numbers over time?

[giroup01]

Trichlor is basically CYA with three chlorine molecules attached to the three nitrogen atoms of the CYA molecule (hence the tri- in trichlor).

In water the chlorine detaches and does its work, and you're left with just the CYA molecule.

That's the simple explanation.

[jhm]

That's the simple explanation.

That's actually a great explanation, thank you. So a friend has been feeding his vinyl pool trichlor for years. His CYA is over 100. I've told him to keep his chlorine high, but to only use bleach. Will this damage his liner (I have a plaster pool so I don't know)? How long will it take to get it down to more reasonable levels?

Thanks!

[Watermom]

Only way to lower is to do a partial drain and refill. No more trichlor or dichlor for this pool.

[aylad]

Using the bleach won't damage the liner, especially with CYAso high. Low pH, on the other hand, can do a number on a liner. In addition to raising CYA, trichlor also lowers pH. Might want to check on that....

Janet

[chem geek]

Just make sure that when the bleach (or any concentrated chemical) is added to the pool, it is added slowly over a return flow with the pump running, preferably at the deep end. For extra safety (especially if this is a vinyl pool with no floor drain or if circulation is poor), lightly brush the side and bottom of the pool where you added the chlorine to ensure thorough mixing.

Bleach is fine when thoroughly mixed, but it is denser than water when concentrated so could settle to the bottom of the pool if you dump it in quickly in one spot without circulation/mixing.

[jhm]

Thanks! Lots of great advice as usual. I've already got him drinking the BBB kool aid.