A shocking question!

[psteichen]

Hi, a new pool owner here! I read through Pool School and quite a few posts, and may have missed something, but when it comes to shocking I have a question:

If I read correctly regarding the OFCT, when the shock is complete the FC shouldn't drop more than about one point overnight. I am wondering if this is with or without the pool cover installed. I am imagining that the cover prevents dissipation of the chlorine. Yes/No?

Thanks in advance for any advice!

 

[jblizzle]

Well, I saw JasonLion looking at this and assumed he was answering ... maybe he saw me and thought the same

It should not really make a difference. FC is lost to organics or the sun, so the cover should not matter (the idea of the OCLT is to take the sun out of the equation). The covers can tend to retain the CC (partially blocked from the sun), so having the cover off during the shock process is usually a good idea.

Also the pump should be running through the entire process.

 

[JasonLion]

You shouldn't lose any significant amount of chlorine overnight, with or without a cover. The primary reasons chlorine gets used up are sunlight, followed by people swimming. A cover prevents both of those things, so it prevents chlorine loss as a "side effect". While chlorine can "evaporate", that happens very very slowly in a pool (and fairly quickly in a water sample bottle).

 

[psteichen]

Okay, thanks guys!