To shock or not to shock??

[94ukgrad]

From my reading on this forum over the last 2 or 3 weeks, it is my understanding that I don't need to shock my pool as long as I'm keep the clorine level in the recommended ranges at all times. Is this correct? 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.

I was wondering what the experts on here have to say?

Thanks for your help.......I love this forum.

Mark.

[Watermom]

It is fine to shock weekly and won't hurt anything but you do NOT routinely need to shock your pool as long as:
-- you consistently maintain adequate chlorine levels and never let your cl drop below the minimum level required for your pool which is based on your cya reading
-- you do not have a CC (combined chlorine) reading higher than 0.5
-- you do not lose more than 1ppm of chlorine overnight from sundown to sunup


I very seldom shock my pool. I might if I have had a really large number of swimmers in the pool like after a pool party or if we get a lot of rain where a lot of debris is blown into my pool. Other than that, I rarely shock it.

Hope this helps.

[aylad]

As long as the "recommended" ranges of chlorine that you're talking about are per the best guess chart..
Stabilizer . . . . . . Min. FC . . . . Max FC . . . 'Shock' FC
=> 0 ppm . . . . . . . 1 ppm . . . . . 3 ppm . . . . 10 ppm
=> 10 - 20 ppm . . . . 2 ppm . . . . . 5 ppm . . . . 12 ppm
=> 30 - 50 ppm . . . . 3 ppm . . . . . 6 ppm . . . . 15 ppm
=> 60 - 90 ppm . . . . 5 ppm . . . . . 10 ppm . . .. 20 ppm
=> 100 - 200 ppm . . . 8 ppm . . . . . 15 ppm . . .. 25 ppm

And not the "recommended" Cl from 1-3 ppm, then as long as you maintain the recommended levels, you shouldn't have to shock except in the conditions that Watermom mentioned above. I usually shock mine after a few days of heavy use by lots of kids, or after a weather system that was hurricane-generated moves through, but otherwise there's really no need.

Janet

[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 (http://www.troublefreepool.com/pool-water-chemistry-t628-20.html#p206863) and in another forum I wrote about how chlorine is not like an antibiotic where resistance from mutation was possible in this post (http://x.havuz.org/viewtopic.php?p=26832#p26832).

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.