CH going up and up


Silver Supporter
Nov 25, 2019
Riverside, CA
Hello all, the CH has been going up since filling the pool. I suspect normal evaporation plus, once I added a small amount of calcium months ago. I will never add calcium again and I have a pail of it if anyone wants it for free. Fill water has a CH of 140. I need to test the water sitting in the autofill vault.

My question is will a breakdown of tile grout exposing concrete from the shell causing CH rise? I have rapid calcium accumulation under my spillover and on the edges of the copper spa scupper where it meets the tile. If this scupper seal was compromised and water was running under it and over the shell would this erosion/leaching cause CH rise?

I do need to clean the filter for the first time. There may be rocks from concret sitting in it eroding away.

I may get a RO treatment truck over which is about $600 to clean this up and see how long it lasts.


Gold Supporter
TFP Guide
Nov 12, 2017
Central California
Pool Size
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
CH accumulation happens in most every pool. CH doesn't evaporate, so as you add fill water (which has calcium in it), you add calcium that never leaves. You lose some from splash out, or if your pool overflows during heavy rain, but that's about it. You reduce calcium by exchanging water. Or you can virtually eliminate accumulation if you top off your pool with soft water (that's how I do it, let me know if you want more details about that).

I suppose calcium could be coming from the crud in your filter, or from the decomposing grout or other erosion of your pool materials. Our experts can weigh in on that. But that erosion is not normal, so you may have other issues to resolve.

The other accumulation you're seeing, on the spillover and scupper is likely effervescence, but that white material is coming from the water (I think it's calcium), so that wouldn't add to your calcium level, because it's already a component of your water's chemistry.
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Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
Laughlin, NV
In your environment I doubt your evaporation would exceed much more than one full pool volume a year. Maybe 1 1/2. So if you start with a CH 140, after one year you would be around 300. I did not look at how much calcium you added, but that is one product that is rarely needed in So Cal.

Your data shows neutral to positive CSI so it is doubtful any calcium is coming from your pool structure.

You do not indicate in your signature but I hope you have your own proper test kit. And for high CH testing, a Speedstir is a must.
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