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Thread: How do I lower pH without lowering TA?

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    How do I lower pH without lowering TA?

    I'm sure this is a stupid question - I've gone through the Pool School several times and have run my numbers through the Pool Calculator, but can't seem to wrap my head around this one area.

    This is a new pool - still trying to get to an initial balance. I've added salt for the SWG - pump has been out so I've also been adding liquid chlorine. Pump has been replaced so I'm ready to continue with everything else.

    Based on my K-2006 tests my TA is 60 and my pH is 7.7. So how can I lower pH without lowering my TA? (My pump was out for 2 weeks. The installer put a temporary pump on the side of the pool that pumped water out and right back in. He said it was to keep the water circulating. I'm guessing that this aeration going on all day is what caused my pH to increase. pH from the week before was 7.4.)

    I'm going to start adding CYA today, sounds like this might take a while - and once I get TA and pH set I'm going to start with the borates.

    Thanks!
    34K gal IG, 37'x40' lagoon, vinyl, Pentair IntelliFlo VS Pump, 500# Hayward sand filter, Jandy SWG, Raypac heat pump, 4 deck jets, Hayward Super Pump + deck fountain, Dolphin Oasis Z5

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    steinholder's Avatar
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    Re: How do I lower pH without lowering TA?

    Greetings... at the bottom of the pool calculator, there is a tool that allows you to see what the different chems will do for your pool.

    http://www.poolcalculator.com/
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    Re: How do I lower pH without lowering TA?

    If your pH stays steady at 7.7, I don't see a need to lower it.

    If your pH rises above 7.8, you will have to lower it using acid and then add baking soda to raise your TA.
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    Re: How do I lower pH without lowering TA?

    Quote Originally Posted by steinholder
    Greetings... at the bottom of the pool calculator, there is a tool that allows you to see what the different chems will do for your pool.

    http://www.poolcalculator.com/
    Thanks - I have seen that, and that's part of my question - if I lower pH to say 7.4, The Pool Calculator says I'll also be lowering my TA by more than 7. So then I'll need to raise my TA - which seems like that would raise my pH? Seems like I'm stuck in a endless cycle.
    34K gal IG, 37'x40' lagoon, vinyl, Pentair IntelliFlo VS Pump, 500# Hayward sand filter, Jandy SWG, Raypac heat pump, 4 deck jets, Hayward Super Pump + deck fountain, Dolphin Oasis Z5

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    Re: How do I lower pH without lowering TA?

    Quote Originally Posted by faby3003
    If your pH stays steady at 7.7, I don't see a need to lower it.

    If your pH rises above 7.8, you will have to lower it using acid and then add baking soda to raise your TA.
    Thanks. I'm just not sure that it is going to be steady where it is. My SWG is on again, kids will be playing in the pool, deck jets, etc.

    Won't the baking soda turn around and raise my pH as well?
    34K gal IG, 37'x40' lagoon, vinyl, Pentair IntelliFlo VS Pump, 500# Hayward sand filter, Jandy SWG, Raypac heat pump, 4 deck jets, Hayward Super Pump + deck fountain, Dolphin Oasis Z5

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    Re: How do I lower pH without lowering TA?

    Quote Originally Posted by Mike_k
    Won't the baking soda turn around and raise my pH as well?
    Very very little relative to the amount of TA increase you get. Put some numbers in the bottom of the poolcalculator and you will see what I mean:

    For a 34k gallon pool, 200 oz of baking soda will raise TA by 26 ppm and pH by 0.05
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    Re: How do I lower pH without lowering TA?

    Quote Originally Posted by jblizzle
    Quote Originally Posted by Mike_k
    Won't the baking soda turn around and raise my pH as well?
    Very very little relative to the amount of TA increase you get. Put some numbers in the bottom of the poolcalculator and you will see what I mean:

    For a 34k gallon pool, 200 oz of baking soda will raise TA by 26 ppm and pH by 0.05
    Oh.... that makes sense. So there's not a way to lower one without the other, but there is a way to raise either without changing the other much or at all.

    Thanks!
    34K gal IG, 37'x40' lagoon, vinyl, Pentair IntelliFlo VS Pump, 500# Hayward sand filter, Jandy SWG, Raypac heat pump, 4 deck jets, Hayward Super Pump + deck fountain, Dolphin Oasis Z5

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    JasonLion's Avatar
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    Re: How do I lower pH without lowering TA?

    They always both move at the same time, but depending on what chemical you use you can get the one you want to change to change a whole lot, and the other change only a very small amount. In all but unusual cases the small change is small enough to ignore. And if the smaller change does need to be corrected, the resulting change in the original number will certainly be small enough to ignore.
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    Re: How do I lower pH without lowering TA?

    Quote Originally Posted by JasonLion
    They always both move at the same time, but depending on what chemical you use you can get the one you want to change to change a whole lot, and the other change only a very small amount. In all but unusual cases the small change is small enough to ignore. And if the smaller change does need to be corrected, the resulting change in the original number will certainly be small enough to ignore.

    This brings up something I often thought about. Since most of us with a SWCG add acid somewhat regularly to lower pH, what prevents the asymptotic drop off of TA to near zero? As a matter of fact, didn't the original pool guru Ben recommend lowering TA by keeping pH low with frequent acid additions (as opposed to waiting for 7.8 and then lowering with a relatively large addition of acid) and constant aeration? This seems awfully similiar to how I maintain the pH in my pool. Weekly additions of small amounts of acid with constant aeration (SWCG and kids). Empirically, I find TA the most stable parameter of all. I've had my pool four seasons now and have never adjusted it other than when we first filled it.
    27ft Above Ground Pool
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    Re: How do I lower pH without lowering TA?

    I've had my pool four seasons now and have never adjusted it other than when we first filled it.
    You are saying that you have an operating SWG and have never had to lower pH in four years?
    Dave S.
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    Re: How do I lower pH without lowering TA?

    Muriatic Acid if broadcast and splashed across the pool surface will lower pH greater than it will lower alkalinity. But administering the same dosage of acid by gently pouring it into a "pocket" without disturbing the surface and splashing will lower alkalinity more than pH. It's interesting how the same product is used to lower both pH and alkalinity, but how you apply it determines which one you have greatest impact on. Whenever you're working with acid, slow and steady is paramount. You do not do it all at once. On day one, only put in 50% of your prescribed dose. On day 2 you put in 25%. On day 3 put in 15%, and on day 4 put in the remaining 10%. This rule allows lowering of your alkalinity while pH has a chance to recover inbetween doses. I have used these methods for years. I also know there are articles out there that have been written in an attempt to disprove this, but the proof is in the pudding. It just works.

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    Re: How do I lower pH without lowering TA?

    Quote Originally Posted by rkgdmd
    Quote Originally Posted by JasonLion
    They always both move at the same time, but depending on what chemical you use you can get the one you want to change to change a whole lot, and the other change only a very small amount. In all but unusual cases the small change is small enough to ignore. And if the smaller change does need to be corrected, the resulting change in the original number will certainly be small enough to ignore.

    This brings up something I often thought about. Since most of us with a SWCG add acid somewhat regularly to lower pH, what prevents the asymptotic drop off of TA to near zero? As a matter of fact, didn't the original pool guru Ben recommend lowering TA by keeping pH low with frequent acid additions (as opposed to waiting for 7.8 and then lowering with a relatively large addition of acid) and constant aeration? This seems awfully similiar to how I maintain the pH in my pool. Weekly additions of small amounts of acid with constant aeration (SWCG and kids). Empirically, I find TA the most stable parameter of all. I've had my pool four seasons now and have never adjusted it other than when we first filled it.

    On another note, what is a too low level of TA? Mine is about 70 now, do I need to add baking soda?
    17,800 gallon, IG pool, 595 sq feet (17x35x4.5 avg rectangle), Hayward 525 cartridge filter, diamondbrite, 2 hp 2 speed hayward tristar filter, Stenner 45mhp10 automatically chlorinating

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    Richard320's Avatar
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    Re: How do I lower pH without lowering TA?

    Quote Originally Posted by march2012


    On another note, what is a too low level of TA? Mine is about 70 now, do I need to add baking soda?
    No. 70 is fine.
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    Re: How do I lower pH without lowering TA?

    Quote Originally Posted by feetr2c
    Muriatic Acid if broadcast and splashed across the pool surface will lower pH greater than it will lower alkalinity.
    So I want to lower pH without lowering TA - you're saying I should splash the acid across the pool surface?

    Or should I do the normal slow and steady and raise TA as needed afterwards?
    34K gal IG, 37'x40' lagoon, vinyl, Pentair IntelliFlo VS Pump, 500# Hayward sand filter, Jandy SWG, Raypac heat pump, 4 deck jets, Hayward Super Pump + deck fountain, Dolphin Oasis Z5

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    JasonLion's Avatar
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    Re: How do I lower pH without lowering TA?

    Quote Originally Posted by feetr2c
    Muriatic Acid if broadcast and splashed across the pool surface will lower pH greater than it will lower alkalinity. But administering the same dosage of acid by gently pouring it into a "pocket" without disturbing the surface and splashing will lower alkalinity more than pH.
    This is a myth, often repeated, but no truth to it at all.

    Constantly lowering PH will lower the TA, but quite slowly. Since it is high TA that makes the PH go up in the first place, this process tends to be self limiting.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
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    Re: How do I lower pH without lowering TA?

    Quote Originally Posted by duraleigh
    I've had my pool four seasons now and have never adjusted it other than when we first filled it.
    You are saying that you have an operating SWG and have never had to lower pH in four years?
    No. I have not adjusted TA in four years......pH is adjusted as necessary......usually weekly.
    27ft Above Ground Pool
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