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Thread: Need to lower pH?

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    Need to lower pH?

    Hello,

    I have been using bleach as our chlorine source since we moved into our new home a couple of weeks ago. Water continues to look clean and clear, but I've noticed that the pH reading has climbed slightly during that time (I use TF-100). PH was at 7.2 back on 6/1, and has since steadily gone up to 7.8 as of this afternoon. Wouldn't be as concerned about it if our CH wasn't so high (previous pool man used cal hypo once a week to shock). Below is a full set of numbers:

    FC = 8.5
    CC = 0
    PH = 7.8
    TA = 80
    CH = 860
    CYA = 100

    I just added enough bleach to raise FC to 10 based on our high CYA. 10 seems to be working well for keeping water nice and clear. We're expecting heavy rainfall this evening and over the next couple of days. Just wondering if I need to be lowering pH, or if it's fine for now.
    23,000 gal. IG gunite pool, DE filter, elevated spa with spillover, Polaris 280 cleaner

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    Mod Squad tim5055's Avatar
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    Re: Need to lower pH?

    Well, obviously the pool guy did you no favors with the CalHypo. I would,say bring the pH down just a little.

    If you could figure a way to harvest rain water you could get that CH and high CYA down for free. I pulled water from one of my roof gutter downspouts, screened it so,trash didn't get into the pool and got free water. Everytime you pump water out those numbers are going down.
    TFP Moderator 39 X 18 23,000(ish) freeform gunite; built 2007ish; Pentair Triton II TR100 600lb Sand filter; 2 HP Pentair pump with 2.2 HP AO Smith single speed motor; 2 skimmers, 1 main drain, 4 returns w/waterfall, Stenner 45MHP2 3GPD running@ 60% - 15 gal Tank; heated by the sun CYA 200+ when I started - 50 now. Dolphin Supreme M5 Pool Cleaner. Hot Springs SX Spa, 285 gallon

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    Mod Squad jblizzle's Avatar
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    Re: Need to lower pH?

    With the high CYA and CH ... I would certainly try to figure out a way to replace water .... drain some of the water prior to the rain and divert it off the house into the pool.
    Jason, TFP Moderator
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    Re: Need to lower pH?

    Unfortunately, draining and refilling isn't something we can do right now. We don't really have a way to catch the rainwater and route it into the pool (at least not before this evening's showers come through). We're hoping to ride out the high CYA & CH this summer, and try to do a drain and refill this fall or winter when water isn't at such a premium. How high is too high for our pH, given the rest of our readings?
    23,000 gal. IG gunite pool, DE filter, elevated spa with spillover, Polaris 280 cleaner

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    Mod Squad jblizzle's Avatar
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    Re: Need to lower pH?

    I would try to keep it between 7.2-7.5
    Jason, TFP Moderator
    18k IG pebblesheen pool, Hayward ProLogic P4 w/ T-15 SWG, Pentair 1HP 2-speed Superflo, Hayward 6020 DE filter
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    Scuba_Steve's Avatar
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    Re: Need to lower pH?

    I am not a calcium expert by any means. The CSI on the pool actually is not that bad though. Anything above 8.0 throws it into the too high realm.
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    Re: Need to lower pH?

    Since getting some rains and very high winds the other night that blew lots of debris into the pool, I'm now getting a slight CC reading (the clear mixture from the FC drop test turns a very slight/barely noticeable pinkish when I add one drop of reagent for the CC test). As I understand it, I now need to raise the FC to shock level. According to the pool calculator, shock level of FC is 25 ppm based on my amount of CYA (100). I now have a couple of questions:

    - My pH is still 7.8 (I had not added muriatic acid yet, since rain was coming and I wasn't sure if that would have affected it). Do I need to lower the pH before I raise FC to 25?

    - Once I do raise FC to 25, do we need to wait until the FC drops down to a certain level before we can swim (including small children)?
    23,000 gal. IG gunite pool, DE filter, elevated spa with spillover, Polaris 280 cleaner

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    Richard320's Avatar
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    Re: Need to lower pH?

    We treat .5 CC or less as zero here. You don't need to SLAM the pool just for that. If there's no algae on the walls, no cloudiness, no sudden loss of FC, it's not called for.
    16K freeform gunite with spa; Pentair 4000 DE filter; Century Whisperflow 1 HP; Pentair Minimax heater.
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    gtemkin's Avatar
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    Re: Need to lower pH?

    From my memory of the CC test, you add 5 drops of R-0003 to your 10ml FC test solution. If the solution is pink, you then add R-871 until the solution turns clear again.

    Your description sounds like you added just 1 drop of R-0003, not 5 drops as suggested.

    If you did perform the test correctly and only 1 drop of R-871 was required to return the 10ml test sample back to clear, that shouldn't drive you to perform a SLAM at shock level. That small amount of CC is what would normally be expected after a storm and will probably return to 0 within a day or so. Just keep your FC towards the higher end of your normal range and you should be OK.
    21K gal 16' x 40' in-ground pool built 1959, old school with Jacuzzi bronze pump, American Products 24" Sand Filter & Americana Multiport valve, Jandy Lite2 millivolt heater, Coverstar cover, and classic Kreepy Krauly.

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    Re: Need to lower pH?

    Yes, I misspoke about how I performed the CC test. Once I had the clear solution from adding R-871, I did add five drops of R-0003 to check CC. The five drops caused the clear solution to change to a barely noticeable pinkish tint. I honestly wouldn't have noticed the difference in color, until I added one drop of R-871 to see if that made it any "clearer", and it did. That told me that my reading was 0.5.

    The water continues to look clean and clear (debris from the storm was pretty easy to scoop out - mostly leaves). I just assumed that any CC reading called for shock, and my CC had consistently been 0 before all of that wind. Good to know!
    23,000 gal. IG gunite pool, DE filter, elevated spa with spillover, Polaris 280 cleaner

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    Mod Squad pooldv's Avatar
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    Re: Need to lower pH?

    Water is not at a premium around here these days. The dams have been open and the lakes 10-15 feet above conservation pool for a month with flood warnings every time it rains.

    The biggest problem is that the CYA test only reads to 100, so the CYA could be 200, 300, we've even seen 700 this year. Target chlorine level for 300 CYA is 36 ppm and shock level is over 100 ppm.

    Shock level for CYA of 100 is 39, Chlorine CYA Chart
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