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Thread: PH Drift from aeration

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    Join Date
    Apr 2014
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    PH Drift from aeration

    So after lurking for 2 years I made the plunge this year, joined the site, ordered my TFT test kit and went with the BBB method. SLAM'd pool, all is good and #'s are in check, added borates and all is essentially beautiful. Except for the darn lingering PH drift. Even after adding the borates I am drifting up from 7.6-7.8 to close to 8+ after 4 days or so (I travel). I think it is because the cleaner/SWG is plumbed so that whenever they run the return is split between the attached spa and pool so the spa over-flows into the pool. To make matters worse we also have an infinity edge so probably too much aeration. I am attaching a pic of the valve that controls the flow between pool and spa. Even when it is set to pool return (i.e. during cleaning) you can see a secondary spa return with the check valve (below the main spa return line) is BEFORE the Jandy valve so even though it is supposed to be "all pool return" so much water is still going into the spa it creates a waterfall of about 3' into the pool. Can I just shut off that secondary spa return (it has a manual valve on it)? Or is there a better solution? Thanks.

    photo.jpg

    Pool Stats:
    45,000 gallon
    PH- 7.6-8.0+
    FC- 6
    TA- 90
    CYA- 70
    Salt- 2900
    Borates- 50

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    JasonLion's Avatar
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    May 2007
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    Silver Spring, MD
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    Re: PH Drift from aeration

    In the photo, I see a blue handle on a lower pipe that appears to bypass the valve actuator. I believe that if you close that valve the spa will stop spilling over when in pool mode.

    You can greatly reduce the PH drift if you lower the TA to 50. Since you are using borates, TA at 50 should be fine. The lower TA will at least lessen the rate of PH increase, though with a negative edge I doubt that it will stop it. If you have a plaster pool and do lower TA, you may need to raise CH slightly to compensate. You don't list a CH level or your pool type, so this might not apply.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

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    Re: PH Drift from aeration

    I see a tab feeder, is that ever used?

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    Re: PH Drift from aeration

    Thanks for the responses. Yes- blue handle will shut it off, but I don't quite understand the design of the system if the spa bypasses the Jandy valve anyway? They essentially "forced" spa over-flow in pool mode. Also, if I turn off the blue handle the spa water never changes out. I guess I need to re-plumb maybe with a 3 way so I can have pool, spa, and combo. I will work on lowering TA- never considered running it that low. Currently CH is already a little high (400) and pool is plaster so I'll check pool calculator and make sure I am OK.
    There is a chlorine feeder but I have not needed to use it since I switched to BBB.
    Thanks.

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    JasonLion's Avatar
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    May 2007
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    Re: PH Drift from aeration

    Your automation system has a spa spillover mode that can be turned on even when the blue valve is closed. One common approach is to program the automation system to run in spillover mode for about an hour each day.

    Bypass setups that always route some water to the spa spillover are fairly common. They give you a choice about how you want the system to work, constant spillover, programmed spillover, or no spillover.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

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