SWCG and PH increase

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JB007

JB007

Silver Supporter
Apr 3, 2022
86
Houston
Pool Size
17000
Surface
Plaster
Chlorine
Liquid Chlorine
SWG Type
CircuPool RJ-60 Plus
Was going to install a double Stenner pump for MA & LC injection, but the more I read about SWCG, the more I am getting convinced that may be a better way for the chlorine part. Still planning on using Stenner pump for MA.
The only thing that scares me is the PH issue. From my readings, PH seems to increase a lot more with an SWCG than with LC.
What type of increase am I looking at ? 20% - 50% ???

Right now (I just came out of a re-plaster (4 weeks ago)) and I was able to drop my Alkalinity to 85 with a PH that increases about 0.4 in 2 to 2.5 days. So in order to keep my LSI in range, i need to add about 18oz every 2-3 days.
CYA is at 35
Cal 320
I keep PH between 7.6 and 8.0. giving me an LSi range of -.06 to .35
This pool is 17,000 G.
 
JB007 said:
Was going to install a double Stenner pump for MA & LC injection, but the more I read about SWCG, the more I am getting convinced that may be a better way for the chlorine part. Still planning on using Stenner pump for MA.
The only thing that scares me is the PH issue. From my readings, PH seems to increase a lot more with an SWCG than with LC.
What type of increase am I looking at ? 20% - 50% ???

Right now (I just came out of a re-plaster (4 weeks ago)) and I was able to drop my Alkalinity to 85 with a PH that increases about 0.4 in 2 to 2.5 days. So in order to keep my LSI in range, i need to add about 18oz every 2-3 days.
CYA is at 35
Cal 320
I keep PH between 7.6 and 8.0. giving me an LSi range of -.06 to .35
This pool is 17,000 G.
Click to expand...
It’s not actually a thing. It’s just that using acidic trichlor tends to hold the pH down more than liquid so when you switch it just seems like the pH rises faster cause no more acidic trichlor is being used.
 
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so are you saying that if all chem stats remains as they are (like in the case above), there would be no change to the PH measure and changes ?
 
JB007 said:
The only thing that scares me is the PH issue. From my readings, PH seems to increase a lot more with an SWCG than with LC.
Click to expand...
My TA is 60, and I have a SWCG. I only used MA once last year at the end of the season while closing. Pool sat at 7.4 all summer.
 
Last edited:
People switching from trichlor (solid chlorine) to SWCG gave rise to the urban legend of SWCG causing pH rise. It's a myth.

Your new plaster is causing TA to rise, which causes pH to rise faster. That will slow down over time. Some say one year and done. I personally believe it's longer than that and never entirely goes away but becomes unnoticeable / immaterial after around three years. The effect on TA is fast with new plaster and then gradually reduces.
 
High TA Fill water (especially in Houston) will be by far the greatest influence on pH rise. New plaster is second (after about 60 days).
 
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