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Thread: pH drifting up, but why?

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    Join Date
    May 2016
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    Belews Creek, NC
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    pH drifting up, but why?

    This is really the first full season of owning our house with a pool. I opened it to a swamp this year, did the SLAM, got the water clear and since then, Ive used 4-5 of the Trichlor pucks in the chlorine generator and a couple pound packs of shock for chlorine, but mainly to get some CYA in the water as well since I had none.

    Over the past month that the pool has been open, post SLAM, Ive noticed a trend I cant put my finger on.

    Chemistry wise:
    TA: 80
    CH: 200
    CYA:50 (I keep this a little higher because the pool is on the N-NE side of the house and is 95% sun exposed during the day)
    FC: 2-4 (Ive found adding about 1/2 gal of 10% bleach every other day is about right)

    pH is whats bothering me. I use pH Down instead of MA, and twice within the past month, Ive had the pH slowly but steadily drift from 7.2-7.3 to 7.8+. Usually a dose of pH Down fixes the issue, but Im trying to understand why. The only major change Ive made lately is adding a pump timer that runs the pump 6 hours a day, usually from 10pm to 4am.

    Thoughts?

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    duraleigh's Avatar
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    Re: pH drifting up, but why?

    Generally, there is a natural tendency for ALL pools to rise as they outgas. aeration and waterfalls speed that up but they still almost all rise.

    Muriatic acid is a bit cleaner way to keep pH down (cheaper? I don't know) but that's your call.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    mikemass's Avatar
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    Re: pH drifting up, but why?

    Dosing about twice a month? You are a lucky one. Seriously, that is not bad at all.... But.....

    7.2 - 7.3 is a little too low to try and maintain. The "bounce" from there to 7.5 is probably quick and then the move from 7.5 to 7.8 is probably slower. That is range you should be shooting for anyway. You could try and bring the TA down a bit to see if that helps. But what you are describing is not abnormal.
    25 + year pool owner. Current pool (going on 11th year) - 38K gallon in ground Gunite/White Plaster, Spillover Spa, Hayward Cartridge Filter, Hayward 450k BTU NG Heater, Hayward Goldline Aqua Logic control with T-Cell-15 Salt Water Cell, Dolphin Explorer.
    You Need: Bleach, a A Test Kit & a Bookmark to "Pool School". Now what's your question?

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    Texas Splash's Avatar
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    Re: pH drifting up, but why?

    I would give you the things to consider this season:
    - Watch your FC. Its low right now. Your target is 6 based on your CYA and should never be below 4. I add 1/2 gallon (2.5 ppm of FC) to my pool every evening as part of it's algae-free diet.
    - pH will naturally rise as noted by others, but you might also benefit by lowering your TA just a little more; try 70, then 60 if needed.
    - Remember that as it gets hotter, generally that means more water replenishment from evaporation. When you add new fill water, it usually has a higher TA (maybe even pH) so those together might rise as you add more water following evaporation.
    Pat (a.k.a. Texas Splash) ~ My Pool: Viking Fiberglass; 17,888 Gal; Waterway Supreme 2-sp/2-hp pump; Hayward Ctg filter; TF-100 w/ Speed Stir
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  5. Back To Top    #5

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    Re: pH drifting up, but why?

    Ill have the wife up the chlorine tonight when she tests (Im in Phoenix for work and could use the pool!).

    Is lowering TA a water changeout procedure I assume?

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    mikemass's Avatar
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    Re: pH drifting up, but why?

    Quote Originally Posted by cucamelsmd15 View Post

    Is lowering TA a water changeout procedure I assume?
    Nope: Pool School - Lower Total Alkalinity
    25 + year pool owner. Current pool (going on 11th year) - 38K gallon in ground Gunite/White Plaster, Spillover Spa, Hayward Cartridge Filter, Hayward 450k BTU NG Heater, Hayward Goldline Aqua Logic control with T-Cell-15 Salt Water Cell, Dolphin Explorer.
    You Need: Bleach, a A Test Kit & a Bookmark to "Pool School". Now what's your question?

  7. Back To Top    #7

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    Re: pH drifting up, but why?

    Yep, found that right after I posted it.

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