Become a TFP Supporter Pool Math Forum Rules Pool School
Results 1 to 6 of 6

Thread: Shock with Cal Hypo or Bleach?

  1. Back To Top    #1

    Join Date
    May 2009
    Corning, CA

    Shock with Cal Hypo or Bleach?

    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.


    Intex Easy Set 18' x 42" AG
    5400 gal
    Intex Krystal Clear Model 635 pump, 1500 gph
    Type "A" cartridge filter

  2. Back To Top    #2

    Join Date
    Jan 2009
    Cupertino, CA

    Re: Shock with Cal Hypo or Bleach?

    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.
    BBB "Intermediate Swimmer"
    IG plaster pool 18.5K gal, Hayward Pro-Grid DE filter, 3/4 HP Hydramax II; Polaris 380, 3/4 HP booster
    AG spa 325 gal, probably Sundance of some kind
    Water testing instructions on one page

  3. Back To Top    #3
    frustratedpoolmom's Avatar
    Join Date
    May 2007
    SWSuburban Chicago, IL

    Re: Shock with Cal Hypo or Bleach?

    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.
    Helpful links: Pool School; CYA/Chlorine Chart
    24' round AG pool, 52" high, Raypak heater; Waterway 2 spd Pump;
    150 Sq ft. Clearwater Cartridge Filter; Former and DISSATISFIED "Pool Frog" owner

  4. Back To Top    #4

    Join Date
    Feb 2008
    Flower Mound, TX

    Re: Shock with Cal Hypo or Bleach?

    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.
    10K gallon IG gunite with waterfall; Pentair CC320P filter; WhisperFlo 2 HP pump
    TF Test Kits - Pool Math - Pool School
    "It depends."- JohnT

  5. Back To Top    #5

    Re: Shock with Cal Hypo or Bleach?

    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.
    23,000 gallon in ground pool with rock waterfall and spillover spa, Aqualink control system, Polaris 380 cleaner, Purex Triton Clean&Clear Plus cartridge filter. Located in The Woodlands, Texas.

    Pool owner since Nov 2008, Trouble Free since April 2009. Happy to help when I can.

  6. Back To Top    #6

    In the Industry
    duraleigh's Avatar
    Join Date
    Apr 2007
    Sebring, Florida

    Re: Shock with Cal Hypo or Bleach?

    Anona brings up a good point. The longevity of cal hypo makes it desireable to put on the shelf for standby.
    Dave S. - Forum owner
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts