How much muriatic is reasonable?

Drew80

Well-known member
Feb 26, 2013
216
Austin, TX
You can, if you wish. I wouldn't do anything else until it reached 7.8 - 8, then drop it to 7.5 or a bit less. Lower TA levels will slow the pH rise but not eliminate it. Minimize aeration - that is what really drives pH rise because of CO2 outgassing.
If history is any indication, it will be back at 7.8 tomorrow morning. It won't stay at 7.5 for long.
 

Drew80

Well-known member
Feb 26, 2013
216
Austin, TX
In case anyone is interested, I figured out why my pH was rising so much. My CYA levels were lower than I thought, so I was having to generate a lot of chlorine to keep up with sunlight, and that of course causes a rise in pH. I have my CYA at 70 now and I have dropped my chlorine generation from 100% to 50% and I’m still testing and adjusting down every day. My muriatic usage has dropped from about a cup a day to less than a half cup a day and I expect it to drop even more.
 

mknauss

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May 3, 2014
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generate a lot of chlorine to keep up with sunlight, and that of course causes a rise in pH.
The chlorine does not raise the pH. There can be a small amount of aeration caused during the generation of the chlorine. In most pools, that amount of aeration is overwhelmed by other sources of aeration or pH/TA rise due to fill water.
 

Drew80

Well-known member
Feb 26, 2013
216
Austin, TX
Not the chlorine itself, but chlorine generation also creates sodium hydroxide, which is high pH. I've read this in numerous places. Am I completely wrong about that?
 

duraleigh

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If that was my pool, I would bring the TA down to 60 using the acid/aeration method in Pool School......you cannot just add acid and get a permanent drop in TA.

Next, I would check pH every 2-3 days......not everyday.

I believe you will find that you will add the same amount of acid but you will be adding it less frequently.
It raises the pH in the cell itself. The overall chemical reaction is neutral.
+1 on what mknauss said.
 

mguzzy

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Jul 8, 2015
2,039
OV, CA
This is essentially from another post... but I'll be happy to spread the love... Get off the TA/pH hamster wheel. (I stole that line from @mknauss ) Don't chase the TA.. it will equilibrium with your pH when it gets in range. Every few years I find the right balance and my pH hovers around 7.8 without having to add hardly any MA. Otherwise its just a fact of life with a SWG in the family.
 

Drew80

Well-known member
Feb 26, 2013
216
Austin, TX
@mguzzy I'd love to get off the hamster wheel - that's actually what I'm trying to do. I'm not measuring TA all that often. My issue is that my pH keeps going up above 8 and I have scale to show for it. My theory was that the extra chlorine generation from having low CYA was causing the pH to rise, but apparently that's not it.

So if it's not from chlorine generation, why do salt water pools use more muriatic than other pools?
 

JJ_Tex

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Jul 17, 2019
1,308
Prosper, TX (DFW)
@mguzzy
So if it's not from chlorine generation, why do salt water pools use more muriatic than other pools?
I'm not sure that is 100% accurate and my understanding is that the chlorine generation of a salt water chlorine generator is pH neutral. With that said, if you are comparing that to a non salt water pool that uses pucks, the pucks are acidic and can help keep the pH down. So not necessarily true salt vs non-salt, but you can use more acid if you are not using acidic pucks.
 

JimMarshall

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Jun 5, 2017
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Oil City PA
@mguzzy I'd love to get off the hamster wheel - that's actually what I'm trying to do. I'm not measuring TA all that often. My issue is that my pH keeps going up above 8 and I have scale to show for it. My theory was that the extra chlorine generation from having low CYA was causing the pH to rise, but apparently that's not it.

So if it's not from chlorine generation, why do salt water pools use more muriatic than other pools?
It's not from the chlorine generation itself, it's from the aeration that is a by-product of the chlorine generation. Generating chlorine with a SWG does not increase pH, but it does cause aeration, which will increase pH at high TA