Shock with Cal Hypo or Bleach?

[DDave]

We will be leaving town on Monday and returning on Thursday. No one will be available to add chlorine to the pool. On advice from this forum (thanks FPM) I will be shocking and covering the pool while we are gone as a preventitive measure. The pool water is nice and, um, as clear as can be expected with an Intex filter. Actually, it does look pretty good other than the occasional sand and grass that gets tracked in from swimmers but I have been vacuuming once a week.

I have been tapering off on my use of Trichlor as the CYA comes up. I have been adding bleach to maintain appropriate FC levels since the Trichlor reacts so slowly. My CYA level (as of last Saturday) was 30 and I will be testing it again this Saturday to determine the appropriate shock level.

My question is should I use bleach to shock or the 48% Cal Hypo? I have some Cal Hypo (hth Shock and Swim) left from when my wife bought the pool supplies this year at WalMart (before I discovered TFP ) but I am not that concerned if the recommendation is to just dispose of it. Is there any advantage to using the cal hypo over bleach? Any disadvantage? My CH is 150.

Thanks.

Dave

 

[PaulR]

The Pool Calculator has an "effects of adding chemicals" section near the bottom that can help with these sorts of questions. In a 5400 gal pool, it says 1lb 48% cal-hypo raises FC by about 10, CH by 7. So I'd say go ahead and use up the cal-hypo, your CH is starting out low enough that it won't matter.
--paulr

 

[frustratedpoolmom]

It has a long shelf life. You can save it, or you can use it, or use bleach. Just make sure you pre-dissolve it in a bucket of water, make sure it's not dissolving on the liner.

 

[257WbyMag]

Yes, you can go ahead and use your cal-hypo. Since it doesn't add any CYA, you won't run into any problems with messing up your stabilization. You have more than enough leeway on your CH to be okay with it.

 

[anonapersona]

I'd vote to save the cal-hypo, at least several doses of it. Not that I am being contrary just to be contrary.... I think it is good to use bleach first, when you can get it at a good price and/or have it on hand, because bleach degrades. Cal-hypo will be fine for a long time so it is just the thing to use when you need chlorine and are out of bleach and it is too late at night to go get some.

So, use some now, if you have a lot on hand. But save some of it for later on.

 

[duraleigh]

Anona brings up a good point. The longevity of cal hypo makes it desireable to put on the shelf for standby.