PH is always on the rise

[Mical718]

Ok so my pool was redone this year. Went from paint to plaster with a qaurtz by anthony & sylvan. I know they said at first the ph would rise from plaster dust. But we opened before memorial day. Its 2 months now and the ph still rises. Every morning when i check it is always 8.2. I lower it to 7.6 with muriatic acid and within a day or two its right back at 8.2. Heres this saturday test with tf100
7-11--15

Ph 7.8
Fc 2.5
Cc 0
Calcium h 250
Ta 90
Cya 30

 

[chem geek]

Is the TA or CH rising as well? If not, then the plaster is still "sealing" by converting calcium chloride into calcium carbonate. Either that or you have carbon dioxide outgassing. Both processes look the same.

If you had plaster dust and dissolving of calcium carbonate, then the CH and TA would be rising in addition to the pH. When calcium hydroxide in the plaster takes bicarbonate from the water and becomes calcium carbonate, the pH rises with no change in CH or TA. This is actually better than having plaster dust. Just keep your water over-saturated with calcium carbonate as you have been doing and it should settle down as the plaster more fully seals. Though there may still be some slow curing occurring that produces more calcium hyroxide, it's more likely that the existing calcium hydroxide in the plaster is just solidifying to calcium carbonate.

If your pool builder had used a bicarbonate startup instead of the more likely acid or traditional startup, then the plaster would have sealed off more quickly with virtually no plaster dust nor CH or TA rise, not even initially.

 

[Mical718]

Thanks chem geek.... I had a hard time understanding all that so let me just tell you the part i can answer so maybe you can make me understand my situation better..... The ta and ch is not rising. For startup, it was just my hose water with two bottles of jacks magic. Thanks again

 

[chem geek]

Do you have any aeration sources in your pool such as waterfalls, spillovers, fountains, etc.? If so, then you could let the TA drop as you add acid over time to control the pH. Don't add any baking soda to raise the TA until it gets to 70 ppm. Also don't add acid until the pH gets to 8.0 and then only add enough acid to get it to 7.6. See if that helps with the rate of pH rise over time. If it does, then you can consider raising your CH a little, but you can wait until you see if a lower TA helps.

 

[Mical718]

I have a waterslide i can use for aeration.