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Thread: Alkalinity

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    Join Date
    Jul 2015
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    Patterson, Ca
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    Alkalinity

    Pools 5 months new but alkalinity runs at 120 130 and PH 7.6 - 8 when I take down to 90 range it only lasts a day or two before running at 130 again. Almost three fourth a gallon of acid used to bring down alkalinity. Waters been Crystal clear since start up. But just wondering if this is natural. And I fix it once to twice a month.
    17k g, IG free formed, plaster/bella blue,varaible pump, cartridge filter, with water feature.New build 6/17/15 builder set start up and pump filter cleaning time. Runs 12am-2am clean cycle runs 2750 rpms n from 2am-8am 1200 rpms

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    Texas Splash's Avatar
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    Re: Alkalinity

    ARV, I pulled this quote from the Plaster Start-Up page:
    No matter what start-up procedure is used, your pool will consume a lot of acid during the first 6-12 months as the plaster finish continues to cure. It is important to test your pH daily and do not let it climb above 7.8. Be sure to continue to brush the pool at least weekly during this period.
    Since we know PH and TA like to run together, it seems to make sense they are creeping-up together each week, and that constant vigilance (and acid) are the prescription for the time-being.

    But quick question ... am I reading your post or signature wrong? "New build 6/17/15 (2 mos), but your thread starts-off with 5 months. Maybe you're still in that break-in period? Maybe others will have a thought or two.
    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
    Vital Links: POOL SCHOOL, RECOMMENDED LEVELS, RECOMMENDED CHEMICALS, Poolmath Calculator, SLAM, Chlorine/CYA CHART.
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  3. Back To Top    #3

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    Patterson, Ca
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    Re: Alkalinity

    Thanks for the help.
    17k g, IG free formed, plaster/bella blue,varaible pump, cartridge filter, with water feature.New build 6/17/15 builder set start up and pump filter cleaning time. Runs 12am-2am clean cycle runs 2750 rpms n from 2am-8am 1200 rpms

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    May 2014
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    Cookeville,TN
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    Re: Alkalinity

    I'm on the newbie side of things, so I'm curious to the possible reasons for this situation, because my pool dynamics are far different. Mine creeps up ph wise but TA has never moved up on me unless I added baking soda to manually move it back up. Acid temporarily drops my ph, yet permanently drops my TA. The way it always went for for me until recently was that, keeping my TA 70-90, I'd have to add acid about four days per week, and every two weeks or so I'd have to add baking soda to raise my TA. TA would always fall to around 50 over this two week period just as the calculator shows it will. I'd continue this same cycle all the time until Chem Geek gave me the solution. On this last cycle, I lowered PH down to 7.5-7.6 each time it crept up out of range as usual. but this time, I just kept adjusting down until it quit creeping back up, and didn't worry about the TA. Now my TA is around 40, but my PH stays in range, and it's CG approved.

    But this post interest me, because through my own experience, I wouldn't have thought that TA could move back up after acid doses. In my experience, TA moves down with acid and stays down, while ph may or may not come back up.

    But plaster makes things a little different, so I'd like to learn more.
    7600 gallon; 18'X54" round; vinyl; sand filter and 110V pump, 2-speed.
    Near Cookeville, TN--1/2-way between Nashville--Knoxville along I-40; Highland Rim part of the Appalachian Plateau (we call the Cumberland Plateau for the southern half of this geological region).

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    Texas Splash's Avatar
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    Re: Alkalinity

    One of those reasons we hear that saying a lot that "Every pool is unique". Some pools it's plaster that has a strong influence, for others it may be the amount of swimmers, aeration (intentionally or unintentionally), pools that have an SWG, etc. The list goes on I'm sure. But inevitably, one pool may rest well with a TA of 60 and PH at 7.4, then their neighbor's pool has a TA of 110 and ph of 7.6. Both happy with few fluctuations. Me personally, my pool likes a TA of about 60-70, and the ph almost always stays in the mid 7s. From time to time, I like to go back and read some of these:
    Pool School - Lower Total Alkalinity
    Pool School - Recommended Pool Chemicals
    Just reminds me of the basics.
    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
    Vital Links: POOL SCHOOL, RECOMMENDED LEVELS, RECOMMENDED CHEMICALS, Poolmath Calculator, SLAM, Chlorine/CYA CHART.
    If you enjoyed your TFP experience, please consider donating to Support TFP!

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    San Rafael, CA USA
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    Re: Alkalinity

    Acid always lowers both pH and TA, without exception. What is different in each pool is the source of pH rise. If it is from carbon dioxide outgassing, then that raises the pH with no change in TA so the net effect of acid addition to maintain pH will be that the TA lowers over time.

    For a pool curing or degrading with plaster, there are different things that can happen. The best is that the plaster forms a hard calcium carbonate surface "in place" with no plaster dust. In that case it will look just like carbon dioxide outgassing. The not-so-great cases are that instead the calcium hydroxide from plaster curing either dissolves directly into the pool or the calcium carbonate that is formed dissolves into the pool. Both of these will raise not only the pH, but also the TA and the CH. The table in this post shows these different scenarios before acid addition that would lower the pH and TA.

    The TA and CH can also rise from evaporation and refill since water almost always contains some TA and CH so that gets added to the pool.
    16,000 gallon outdoor in-ground 16'x32' plaster pool; Pentair Intelliflo VF pump; Pentair IntelliTouch i9+3s control system; Jandy CL-340 square foot cartridge filter
    12 Fafco solar panels; Purex Triton PowerMax 250 natural gas heater (200,000 BTU/hr output); automatic electric pool safety cover; 4-wheel pressure-side "The Pool Cleaner"

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    Agent99's Avatar
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    Aug 2008
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    San Jose, CA
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    Re: Alkalinity

    I'm on day 28 of a new Pebble Sheen finish on my pool. I've added A LOT of 14.5% MA since then to keep the pH down. My fill water came in at 120 TA and after several gallons of MA over the 4 weeks, my TA hit 70 and I tossed in 3 quarts of baking soda and that bumped the TA back up to 100. I still add MA a couple times a week to keep the pH in check. My CH is steady at 230 and CYA around 40. Water is crystal clear and a pleasure to swim in.
    ----Chris----
    25k IG/Spa Figure 8, 18x36, Pebble Sheen Blue Granite, Sta-Rite S8M150 Cartridge Filter, Pentair 460805 400k BTU Heater & 011018 IntelliFlo VarSpd
    Liquidator, Fafco Solar Heat, Polaris PB460 Booster Pump w/280 cleaner, Katchaleaf Cover, TF100 Test Kit, FAKE MAIN DRAIN

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