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Thread: Persistent Problem with High Total Alkalinity

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    Persistent Problem with High Total Alkalinity

    Recently retired, I have taken over the pool maintenance responsibilities from my former pool man. My pool was replastered about 5 months ago. It has 15,000 gallons and a 3/4 hp pump by Pentair. My pool is clear, and all chemicals are in the acceptable range except for the TA. My PH had been over 8 about a week or so ago. It is now down to 7.8. My TA had been around 190 or 200. I have been adding MA for a week. I had been adding about 26 ounces a day with the pump running until last night. Although this has brought down my PH the TA was only coming down a little bit. Last night I added 48 ounces of MA into the deep end with the pump off. I waited 1 hour then turned it on for 12 hours. This morning my PH is unchanged. But the TA is UP to 220!? I can't figure out how to get the TA under control. How much more MA can I safely add to my pool? Thanks, Mike

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    Re: Persistent Problem with High Total Alkalinity

    My understanding is the MA should be applied by pouring in front of a running return so that the acid doesn't pool.

    What is the TA of your fill water?
    17,250 gallon plaster pool & spa, IC40 SWCG, Cartridge Filter, CYA 70-80, Boric 50 ppm, Temp~84F, Naples, FL.

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    Re: Persistent Problem with High Total Alkalinity

    Last night I added 48 ounces of MA into the deep end with the pump off. I waited 1 hour then turned it on for 12 hours.
    That's a dangerous old wives tale. You do not want acid sitting on the bottom of your pool.

    When you add acid, pH and TA both come down.....that's factual. How are you testing?
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
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    Re: Persistent Problem with High Total Alkalinity

    I am using a Taylor kit. This morning it took 22 drops for the green color to change to red. 22x10 = 220TA. It was coming down (slightly = 190) before I put the acid in last night without the pump running. Can I keep adding acid until the TA drops to around 120? If so, how much should I add and what should be the intervals? I'm assuming I should add the MA with the pump running? Should I add it to the deep end only or around the pool? Also, do I need to dilute it first? Thank you so much for your reply

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    Re: Persistent Problem with High Total Alkalinity

    I recommend you use pool math and only add the amount that keeps PH between 7 and 8. No dilution needed. Add slowly in front of a return or slowly around the perimeter.

    Also, suggest you make a measurement of the water used to fill your pool. Do you have an automatic pool filler?
    17,250 gallon plaster pool & spa, IC40 SWCG, Cartridge Filter, CYA 70-80, Boric 50 ppm, Temp~84F, Naples, FL.

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    Re: Persistent Problem with High Total Alkalinity

    I do not have an auto pool filler. I simply use a garden hose to fill the pool as necessary. I just tested the water coming out of my garden hose. The TA is around 170-180. The PH is 7.8

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    Why does the PH keep increasing in my pool?

    My water is in good balance right now. Total alkalinity is 100 but the PH keeps creeping up slowly. I get it down to 7.6 and if I do nothing for a few days it rises to 7.8 or 7.9. I'm using Tri-Chlor for chlorination, so the chlorine is not increasing my PH. My pool was re-plastered 6 - 7 months ago. Free and available chlorine levels are steady around 2 ppm. CYA is 60 ppm, and phosphates are at 100 ppm. Any ideas why the ph won't hold steady?

    Thanks, Mike

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    Re: Why does the PH keep increasing in my pool?

    Your TA is a bit high, do you have water features that you run daily?


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    Re: Persistent Problem with High Total Alkalinity

    Bringing your TA down from 220 to 100 should have slowed the rate of pH rise. Did it?

    Your use of trichlor will hold down your pH as it is very acidic, kind of like adding extra acid. The down side to trichlor use is the CYA that is in each puck. Have you tested CYA?
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    Re: Persistent Problem with High Total Alkalinity

    Since I've lowered the TA to a good level the PH is certainly better than it was (well over 8), but it doesn't seem to want to stay at 7.6. Keeps creeping up. My CYA is at 60. So it's in a good range, not too high. But unless I keep adding a little MA the PH rises. I do not have a water feature. So aeration shouldn't be the cause.

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    Re: Persistent Problem with High Total Alkalinity

    Quote Originally Posted by mdames View Post
    Since I've lowered the TA to a good level the PH is certainly better than it was (well over 8), but it doesn't seem to want to stay at 7.6. Keeps creeping up. My CYA is at 60. So it's in a good range, not too high. But unless I keep adding a little MA the PH rises. I do not have a water feature. So aeration shouldn't be the cause.
    Test the tap water you use to refill.

    Weekly acid is a way of life for me. If I add two inches of water, I add a quart of acid.
    16K freeform gunite with spa; Pentair 4000 DE filter; Century Whisperflow 1 HP; Pentair Minimax heater.
    Troublefree does not mean Maintenancefree. It's like brushing your teeth: You can spend a couple minutes a day and pennies a week or go to the dentist once a year and spend several thousand dollars.
    A pool is like a pet - you have to feed it every day, even the days you don't want to play with it!

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