Do I have to shock?

[mjt143]

I have read that you should shock 1 time per week, heavy storm, etc. My question is, do I have to shock is my CC is less than .5. Or can I just shock at .5 or greater? Thanks for the input.

[chem geek]

If you properly maintain your pool with sufficient Free Chlorine (FC) levels relative to your Cyanuric Acid (CYA) level then you hardly ever need to shock. Just shock after a heavy bather load or when there are a lot of organics (leaves, pollen, etc.) that get dumped into the pool and the measurable Combined Chlorine (CC) gets above 0.5 ppm. You should target your FC level to be 11.5% of your CYA level (with an absolute minimum of 7.5% of your CYA level -- don't ever let it get below that).

Richard

[Guest]

buy a good test kit that will tell you FC and CC
don't waste your money on shocking when it isn't needed.

[chem geek]

Thanks Pool User. I forgot to refer to the good test kit, the Taylor K-2006, which you can buy from Taylor online here or from Leslie's here or from other online stores (most pool stores don't carry the K-2006 and the K-2005 they sometimes carry is NOT the same). Or get the even better TF-100 kit here (it's better in that the amount of reagents is more logical and the CYA test measures down to 20 ppm).

The test kits referred to above all have the FAS-DPD chlorine test which accurately measures both Free Chlorine (FC) and Combined Chlorine (CC) up to 50 ppm and with a resolution of 0.2 ppm or 0.5 ppm depending on sample size. I know that pool stores think it's too complicated for most users and it's a little more expensive, but it's SOOO much better and I really don't think counting the number of drops to make a sample go from pink to clear is very difficult (it's similar to the TA and CH tests in that regard).

Richard