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Thread: I go through about a gal of acid every two weeks

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    I go through about a gal of acid every two weeks

    I go through about a gal of acid every two weeks. It will hit 8 and we drop it to 7.2. That lasts 3-5 days. Do you think if I just lower to 7.8 I will use less acid in the long run?
    22,000 Gunite, Cart Filter, Aquarite SWG

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    JasonLion's Avatar
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    Re: I go through about a gal of acid every two weeks

    If you haven't already, let your TA level go down to around 60, and only lower the PH to 7.6 or so. The further you lower PH, the most it will want to go back up. The PH goes up faster when TA is higher and also faster when PH is lower, so you want TA fairly low and PH fairly high to minimize the PH drift.
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    Re: I go through about a gal of acid every two weeks

    I should have posted a full set of numbers. I've been here long enough to know better!

    FC 6
    CC 0
    Ph 7.3 (dropped it yesterday)
    TA 40
    CH 300
    CYA 40

    I had the SWG dialed down to about FC of 3 but we left town a few days and the Ph got over 8 and the black alge reared it's head. I lowered the Ph to 7 and shocked to 20 ppm and scrubed and scrubed and scrubed. The black dots from **** are gone and the SWG is keeping FC at 6. But, like I said, it only takes 3 days or so for Ph to climb to 8. I could try just lowering to 7.6 and see how that works.
    22,000 Gunite, Cart Filter, Aquarite SWG

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    Re: I go through about a gal of acid every two weeks

    Yes, the rate of outgassing is much faster at lower pH, so try just lowering it to 7.6 to see how that goes. By the way, do you have a short run of piping from the SWG to the first return in your pool? If so, see what happens if you point the return downwards. It may be that you have chlorine gas not fully dissolving into the water and that chlorine gas then outgassing from the pool. A lower TA won't help for that particular problem; it only helps to reduce carbon dioxide outgassing.
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    Re: I go through about a gal of acid every two weeks

    It is about a 15 ft run and has always been pointed down.
    22,000 Gunite, Cart Filter, Aquarite SWG

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    Re: I go through about a gal of acid every two weeks

    Do you still have the ozonator you used to have? Do you have 50 ppm Borates in the pool? Your lower CYA level is requiring the SWG to be on longer than it needs to be. We normally recommend closer to 80 ppm to lower the chlorine loss in sunlight which should let you be able to turn down your SWG on-time and that should reduce the rate of pH rise.
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    Re: I go through about a gal of acid every two weeks

    I'm running the CYA low to make the FC more effective. Still dealing with a few stuborn black alge spots I thought with the SWG, cya should be 50-60. There in no ozone. That went away when the SWG was put in. Borates didn't seem to help the ph rise before so after the first time I put it in the, I never put any more in. It has been a long time so there may not be much left. I've been thinking about bring it back up with some boric acid from eBay. I am out of town for a couple weeks so the pool in in my wife's hands.
    22,000 Gunite, Cart Filter, Aquarite SWG

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    Mod Squad jblizzle's Avatar
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    Re: I go through about a gal of acid every two weeks

    Low CYA does not make the FC more effective. While higher CYA requires a higher FC level, you end up needing less FC added since you loose less to the sun each day.

    If you are trying to deal with algae, then having the lower CYA value is helpful since the shock FC level is lower ... but you are not maintaining the shock FC levels (usually done with bleach not the SWG), so you will not likely make much headway with the existing algae.

    If you see algae, you should be going through the shock process.
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