Replaster and pH rising

bparker

Active member
Dec 8, 2015
41
Dallas, TX
#1
The pool was re-plastered on 03/10 and filled with water. Basically white plaster. 1.5 months later pH is still rising. every day or so I add 32 oz. muriatic acid when it gets to 7.8-8.0. Totals about a gallon a week. I was assuming/hoping that would slow down by now.

From K-2006 kit - FC- 1.5, pH- 7.4, TA- 50, CH- 350, CYA- 30. I will ultimately increase the CYA because 1. it will be a Texas summer and 2. this will be a salt pool (but waiting till things settle down before adding salt). When salt is added I'll follow the recommendations for salt chemistry. For now 2 tabs in the skimmer keeps FC about 1.5.

Is pH rise still due to the new plaster and how long till it slows down? Plaster was on a Friday and pool company did not come back till Monday for startup. Pump was not circulating during that time. Don't know if that had an effect on curing.

Bill.
 

JoyfulNoise

TFP Expert
Platinum Supporter
May 23, 2015
14,644
Tucson, AZ
#2
A couple of things -

1. Your plaster will continue to affect your pH for quite a while - 6 months easily and/or up to a year. That's how plaster is, you just have to deal with it.

2. What type of startup process was used? What chemicals did they add to the water?

3. Tablets should not be kept in the skimmer, they are acidic and emit lots of chlorine. When the pump is not running, you're basically creating a highly acidic stew of over chlorinated water which then gets sucked into the pump and equipment pad. That's not good at all for sensitive equipment like SWGs. Tabs belong in a chemical floater.

4. Why are you trying to drop your pH so low? You should target a pH of no lower than7.6 and add acid only when it goes above 7.8. Then, only add enough acid to bring you down to 7.6. Trying to go down to 7.4 is pointless as it creates lots of dissolved CO2 which then only causes the pH to rise faster as it outgasses. 7.6 is a perfectly acceptable pH.
 
OP
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bparker

Active member
Dec 8, 2015
41
Dallas, TX
#5
Thanks guys.

Matt- not sure what they added on startup. I have used only bleach, some trichlor tabs, and muriatic. I'll happily let pH not go so low. I had one set of startup instructions that said to keep it quite low initially.

I keep the pump running at 1000 RPM 24 hrs. and raise it up when the Polaris is running. Lots of trees, so in the summer the pump schedule will get more complex to give periods of better skimming for leaves.

Dave- I had always heard the FC should be about 5% of CYA. I know that CYA is a little low now.

When I finally activate the new SWCG there won't be tabs in the skimmer. I guess after 1.5 months it should be OK to put in the salt? I know SWCG will tend to raise pH, so I will deal with getting pushed from both ends.

Bill.
 

oldguy70

Silver Supporter
Jun 26, 2015
159
Glendale, AZ
#6
I did a re-plaster in March 2015 and still fight rising pH at almost same rate for 2 years. This past weekend added Boric Acid and will see if that works a bit better.