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Thread: fighting PH drift

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    fighting PH drift

    Hi all, been learning a lot lurking on this great site, best resource by far for my new pool. I've been adding a ton of acid, not too surprised since we get a ton of sun, plaster is still only 4 months old, spill over spa, SWG, and lots of happy kids splashing! But I was really hoping it would get better, been putting in around 4 cups mur acid every 2-3 days, and seems like whenever I test my ph its at or very near the 8.0 (I have a Leslie DPD complete test kit, which i use at least every other day). Seems like my TA wont get below 90. also, for the first time today my chlorine is a bit low so turned up the SWG (from 60% to 70% so that will cause even more drift. Anyway, here are my test results as of today, any thoughts/suggestions/ encouragement greatly appreciated!!
    fc 1
    TC 1.5 (I think, only slightly darker
    CC .5
    ph 7.9 (maybe 8)
    TA 90-100
    CYA 50
    ch 280-290

    Thanks!!
    14k gallons, SWG, inground plaster

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    Join Date
    Jul 2007
    Location
    Katy, TX.
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    Re: fighting PH drift

    My first suggestion regarding your FC read is to increase your CYA to between 70-80 by adding stabilizer since this is a SWG plaster pool. This will allow you to reduce your SWG generator back down to a more reasonable setting. Have you gone through the process of lowering your pH to 7.1 -7.2 followed by aeration to bring the pH back up? This will help with your pH drift if you get your TA numbers down to approx. 60. Read-up on lowering TA in the "Pool School". I'm sure one of the expert Mods will be by soon to confirm and suggest other actions.
    Enjoy,
    Duk
    21,500 gal. IGP, Diamond Kote plaster, spa, and waterfall features, flagstone coping w/ flagstone/river pebble decking. Pentair NSFP 60 filter, 2-ea. 2 HP Whisper Flow pumps, 1-ea. 3/4 HP Hayward booster pump for Polaris 3900 cleaner, AquaLink RS6 controls, GoldLine SWG, T-15 cell

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    Re: fighting PH drift

    First and foremost, you need more chlorine. Refer to the FC/CYA chart in Pool School and you will find you need to be in the 3-5ppm range.

    Adding acid to a new pool is a fact of life for perhaps as long as a year. It'll slowly get better but never stop.

    Bring your pH down to 7.2-7.4 with muriatic. Your TA will come down as well.

    You need more chlorine.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    Re: fighting PH drift

    I understand on the chlorine for sure, I've been keeping it at 3+ by supplementin the SWG with pucks here and there but was hoping to get away from that. Other than adding a couple more lbs of stabilizer, which I'll do this weekend, how can I keep the chlorine where it needs to be without going crazy on the SWG? Isn't 70% pretty high?
    14k gallons, SWG, inground plaster

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    Re: fighting PH drift

    Isn't 70% pretty high?
    Perhaps. You actually may have the beginnings of algae that you can't see. I would suggest you pour clorox into the [pool this evening up to around 5ppm or so (the exact amount isn't important) and carefully perform the OCLT. Read what it is and exactly how to do it in Pool School.

    Basically if you lose much chlorine after the sun is off the pool, you DO have algae and will need to shock.

    Since your FC has been so low, I suspect that may be the case.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    JasonLion's Avatar
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    May 2007
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    Re: fighting PH drift

    First, you should make sure you don't have a low level algae problem. Constantly low FC levels are very suggestive of algae. It is possible to have algae and not see it. The SWG prevents the algae from taking over but can never kill it all off. An overnight FC loss test is a good way to find out if you have an algae problem or not.

    Once you are sure you don't have algae, you should raise your CYA level up to between 70 and 80.

    Fresh plaster continues to raise the PH for up to a year, so there is no getting away from adding acid this season.
    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: fighting PH drift

    Unfortunately I screwed up and got the DPD test kit from Leslies, not the FAS-DPD test kit (so no powder, as near as I can tell, is the difference). Is there some powder I can buy to supplement what I already have? Also, I wouldn't say it's been consistently low, up until a day or two ago when the last couple pucks dissolved completely if I think about it, the levels have been 3+ whenever I tested. Not sure if that's better or worse, though.
    14k gallons, SWG, inground plaster

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    JasonLion's Avatar
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    Re: fighting PH drift

    There is only one reagent in common between FAS-DPD and DPD (R-0003). To do FAS-DPD you need R-0870 (powder), R-0871 (drops), and the little tiny blue plastic spoon.
    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: fighting PH drift

    Thanks guys, I'll get the chlorine squared away and try not to stress the ph.
    14k gallons, SWG, inground plaster

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