Quote Originally Posted by chem geek View Post
If you don't have algae (or unusually high chlorine demand or water turning dull or cloudy) and you have <= 0.5 ppm CC, then you don't need to shock. Even if you have some CC that's a little above 0.5 ppm, you could wait a while and see if a sunny day plus some time takes care of it. Usually this would happen after a heavier bather load -- you could shock if you wanted to, but could just wait a day or two instead.

Sometimes if I get a suntan lotion film on the water and am impatient at getting rid of it, I'll shock or use a non-chlorine shock. I use the the latter if my wife is swimming every day and doesn't want to be in at higher chlorine levels. This situation is rare -- I've only done it once and usually I just let the film be as it does clear up if she doesn't keep adding to it every day.

Richard
Thank you, Richard. Unfortunately, I haven't found yet on the board a sticky that deals with these questions.
Here's are some further questions:
1. Suppose the CC is > 0.5 and there's no algae condition. Do I still need to use the "Ben's Table" , or should I use the 10x CC rule? I'm asking because with my CYA level of 56 , the 20 ppm FC level off the Table seems high. How long would it take for the FC to dissipiate and thus enabling a safe for swimming level of FC?

2. If CYA is stable, as I've read here, and since it protects FC from UV, then how come it is still mentioned here in many places that one should shock in the evening, otherwise the FC will be quickly destroyed by the Sun's UV?

3. I'm sure that no such thing as "average bather load" is accurately defined, and that other bio-enviromental factors are involved, but, what frequency can I expect of FC addition in order to mainatin my normal FC level? Is it daily, or twice a week, or what?

4. What's the best thing to do when one goes on a 1- 2 week vacation and the pool is left unattended?
Shock before you leave? Add trichlor tablets?

Please let me know if a FAQ answering all these questions and other, related ones is posted here or elsewhere. If not, I'm sure it would be very helpful and would save a lot of time and bandwidth.