pH and SWG Question

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S

spyder850

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Nov 5, 2013
30
Los Altos, CA
Sorry if this is a stupid question... Since an SWG is a aeration device, can I expect the pH of my pool to rise due to simply running the SWG ? If so, does this happen "quickly" ? I know that will depend on the % setting on the SWG, but it seems to me the aeration provided by the SWG might be minimal.

In my previous topic I noted that my pH was high (8.0+) and have gotten that down with the addition of 2 gallons muriatic acid (could only find ~15% acid at the store I went to) to 7.6. However, in my followup reading, I noticed a comment about aeration increasing the pH.

The reason I ask is my TA is a little high, so I'm considering lowering the pH to 7.2 and using aeration to raise the pH back up. So will just running the SWG be enough aeration ? Or will I need to do something else ?

Thanks in advance !
 
No such thing as stupid questions.

Yes the SWG causes aeration and thus the pH to rise. How fast it rises depends on how much FC you are generating (pump run time + % setting) and what your current pH and TA levels are.

Lowering the TA is a good idea (assuming you do not have a lot of evaporation and fill water that is high in TA). And the SWG will indeed raise the pH back up. The more aeration, the faster the pH will rise. There really is no hurry to do this. You could just run things as normal and lower the pH when it rises OR get aggressive and try to cause more aeration to raise the pH faster.
 
jblizzle said:
Lowering the TA is a good idea (assuming you do not have a lot of evaporation and fill water that is high in TA). And the SWG will indeed raise the pH back up. The more aeration, the faster the pH will rise. There really is no hurry to do this. You could just run things as normal and lower the pH when it rises OR get aggressive and try to cause more aeration to raise the pH faster.
Click to expand...

Kinda what I figured, but thanks for the confirmation :)

Since we're not swimming much with the cooler weather I thought now might be a good time to try to get the TA down. If I undershoot the pH a little, no one is going to know but me ;-)
 
It will actually be easier to lower your TA when your chlorine demand is at its peak.

My water is cold and there is low chlorine demand. I have little change in pH, even with the SWG running (at low % and run time). During the summer I would adjust pH weekly and now it's monthly.

There is no harm in dropping it to 7.2 now. As long as you are still using your SWG as your chlorine source, it will raise the pH. It will just take longer to get the pH back up to be able to knock it back down again.
 
Increased chlorine demand (bather load, warmer temps, sun exposure). = longer SWG on-time = increased aeration (CO2 off-gassing) = increasing pH = more opportunity to knock down pH to lower TA.

If the water is now sub-swimming temp which will mean little or no bather load and there is less sun exposure due to the season that means chlorine demand will drop and result in less SWG run time. Less run time means less aeration. Doesn't that mean it pH would creep up at a lower rate?

Maybe I don't have a grasp on the TA concept. From now until March I have little demand for Cl so my SWG is now running at a small fraction of what it was during the peak summer months. Since no one is swimming in our 57 degree water I just figured those were the reasons why my pH doesn't move much this time of year. Is there another way to lower TA beside adding acid and aerating?
 
You are right. If the SWG is producing less chlorine, then the pH will not rise as fast due to the SWG itself. Although you could setup a fountain or something to do the aeration in the winter as well.
 
My SWG is on 10% a couple of hours a day as I'm trying to lower my FC as well. My in-pool cleaner is vigorous enough to yield some aeration as well (large bubbles of course). Still I'm not expecting my pH to rise quickly, but as I don't know another way to lower the TA, I'm going to lower the pH to 7.2 and let it rise on its own simply as an effort to also lower the TA.

Thanks for all the info. This is a great site !
 
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