To shock or not to shock??

[chem geek]

Is this low level of clorine actually killing the bacteria and whatever else is in my pool? The pool man told me I needed to bring clorine to shock levels at least once a week to actually kill the bacteria in my pool.

Mark,

Most bacteria are killed very quickly at normal chlorine levels -- even at very low chlorine levels. The main reason for keeping the chlorine levels as high as are recommended on this forum is to prevent algae growth and to oxidize bather waste reasonably quickly. Your pool man is wrong about needing to shock to kill bacteria. I just wrote some technical details about this at TFP in this post and in another forum I wrote about how chlorine is not like an antibiotic where resistance from mutation was possible in this post.

Richard

[94ukgrad]

Thanks for advice guys.

[CarlD]

Richard, of course, is right. As long as algae is blooming in your pool, your chlorine will be consumed killing it. With no chlorine you have no way to kill bacteria. That's the real danger. As far as I know, algae itself is not dangerous, but it "sucks out" the chlorine you need to protect you from the dangerous stuff.

Bather waste sounds disgusting but it includes less gross things like sun-tan lotion and other cosmetics, anything that's present on the skin, as well as the less pleasant things.

[chem geek]

The only direct danger with algae, other than the annoying higher chlorine demand, is that it can be slippery and if it is clouding the pool it can prevent you seeing someone drowning at the bottom.