Can I use Sodium dichloro to shock pool?????

[kentuckybob1952]

My pool is doing very nicely this year thanks to all the good info I have learned on this fourm,not to mention all the money saved from not buying all the chemicals from the pool stores. My water readings are TA 100, PH 7.7,CYA 50,FC 5.5, and CC between .2 and .5 depending on which test method I use either 10 ml or 25 ml of water. My pool is 18000 gal vinyl liner and cartage filter. My question is do I need to shock pool and if so can I use some Sodium dichloro-s-triazinetrione that I have left from last year? The lable says it's 99% with 55% available CL. I have only been using liquid CL the past month because I don't want my CYA to elevate. For many years I used the pucks and didn't know about correct readings only what I was told from my local pool store. Thanks Kentucky bob!!!!

[chem geek]

If you use the Dichlor you have, then for every 1 ppm Free Chlorine (FC) you add, you will also be adding 0.9 ppm Cyanuric Acid (CYA). This is even worse, in terms of adding lots of CYA, then using Trichlor where every 1 ppm FC results in 0.6 ppm CYA.

So if you don't want to raise your CYA, then do not use the Dichlor.

Richard

[Buggsw]

What Chem Geek said. He is a genuine master at chemistry.

I'd also be real ginger about using Trichlor at this point. I'd use unstabilized chlorine, such as liquid chlorine.