Where’s the CH coming from?

jimbethesda

Gold Supporter
Jul 2, 2018
528
Austin, TX
My CH rises over time. I’ve turned off my auto fill and now add water exclusively from a water softener. Most recently, my CH went from 600 to 675 despite not adding any water, and I actually had to drain some due to rain.

Where is the CH coming from? Is it leaching from my plaster? Is this normal? Only thing added during that time is muriatic acid, and some baking soda. Salt cell creates the chlorine.

Thanks in advance.
 

Texas Splash

Mod Squad
TFP Expert
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Jun 22, 2014
33,838
Texas, San Antonio/Marion, South-Central Area
Pool Size
17888
Surface
Fiberglass
Chlorine
Salt Water Generator
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CircuPool RJ-45 Plus
Jim, it doesn't appear that your PoolMath is linked to TFP for us to see your testing logs. Can you post some results for us? I could see some CH fluctuation back when your pool was first constructed, but by now it's fully cured and should've stabilized unless you had your water extremely aggressive with a very low pH to pull calcium our of scale into a water solution.

Do you use the speedstir?

Also, there could be some variances by make/model of softener, but it may still be adding some calcium. Last I tested my softener CH is was indeed very low, but there was a little. Does your softened tap water show any CH at all?
 

jimbethesda

Gold Supporter
Jul 2, 2018
528
Austin, TX
I should also probably ask ..... are you using the 10ml water sample size for the CH test? Are the reagents within one year old?
I think it should be linked now.

Yes, I’m using 10ml and speedster. There is some calcium in the water coming out of the water softener. I thought that was what was causing the CH to rise, but this time I didn’t add any due to rain.
 

jimbethesda

Gold Supporter
Jul 2, 2018
528
Austin, TX
Actually, I hadn’t checked CH in awhile now that I look at my logs. I guess I did add water from water softener during that time. Still seems like a steep rise in CH even with low level of CH from water softener.

I used a 25mil sample to test the water coming from the softener. Needed only 1 drop to turn blue.
 
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jimbethesda

Gold Supporter
Jul 2, 2018
528
Austin, TX
Jim, it doesn't appear that your PoolMath is linked to TFP for us to see your testing logs. Can you post some results for us? I could see some CH fluctuation back when your pool was first constructed, but by now it's fully cured and should've stabilized unless you had your water extremely aggressive with a very low pH to pull calcium our of scale into a water solution.

Do you use the speedstir?

Also, there could be some variances by make/model of softener, but it may still be adding some calcium. Last I tested my softener CH is was indeed very low, but there was a little. Does your softened tap water show any CH at all?
So is that it then, must be coming from the hose? Could it still be leaching from the plaster?
 

Texas Splash

Mod Squad
TFP Expert
LifeTime Supporter
Jun 22, 2014
33,838
Texas, San Antonio/Marion, South-Central Area
Pool Size
17888
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
CircuPool RJ-45 Plus
Could it still be leaching from the plaster?
It would seem unlikely unless you went out of your way to drive the pH really low resulting in a very low CSI for an extended period of time.
 
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