How do I lower pH without lowering TA?

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Mike_k

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Apr 16, 2012
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Mason, Ohio
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!
 
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.
 
steinholder said:
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/
Click to expand...

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.
 
faby3003 said:
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.
Click to expand...

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?
 
Mike_k said:
Won't the baking soda turn around and raise my pH as well?
Click to expand...

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
 
jblizzle said:
Mike_k said:
Won't the baking soda turn around and raise my pH as well?
Click to expand...

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
Click to expand...

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!
 
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.
 
JasonLion said:
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.
Click to expand...


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.
 

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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.

Sent from my MB865 using Tapatalk 2
 
rkgdmd said:
JasonLion said:
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.
Click to expand...


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.
Click to expand...


On another note, what is a too low level of TA? Mine is about 70 now, do I need to add baking soda?
 
feetr2c said:
Muriatic Acid if broadcast and splashed across the pool surface will lower pH greater than it will lower alkalinity.
Click to expand...

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?
 
feetr2c said:
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.
Click to expand...
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.
 
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