PH Levels after Newly Plastered Pool

[chem geek]

Also, what is the "range" you are talking about when you write "to bring levels back with in range"? Pool industry standards are NOT correct and when using hypochlorite sources of chlorine (e.g. chlorinating liquid, bleach, Cal-Hypo, lithium hypochlorite) you want your TA lower, even lower than 80 ppm if necessary to have the pH be more stable. This is because TA does not just buffer pH, but is a SOURCE of rising pH in its own right because TA is largely a measure of how over-carbonated water is compared to air.

[markphin]

The TA was 70. So I added enough to bring up to 90. I see what you are saying though. Keep the TA at lower levels and it will help control the PH. Thanks I will keep an eye on that. Things do seem to be slowing down a bit more. Over the last 5 days I've only added about 2 quarts of acid, when up to this point I was adding about a gallon a week.

[CarlD]

The lower TA should help. As the concrete cures the rising pH should end. Do you have anything like a waterfall or fountain or other water effects? They all create aeration which tends to raise pH (but doesn't raise TA--that's why we use it in our TA-lowering strategy).

[markphin]

No fountains. A spillover from the hot tub though. Yeah, I'm sure the PH will stabelize eventually. I just didn't think it would take this long. I'm hoping it stabelizes by the time I winterize in another month or so.

[CarlD]

The spillover could well be part of the reason for a rising pH, because it will aerate the water.

[markphin]

I kind of doubt it, as prior to the replastering, I have had little rise in PH over the couse of the previous 13 years. If I put a gallon of acid in a summer it was a lot. I think its primarily due to the curing of the new plaster. Perhpas the aeration is adding to it a bit though. I guess I just have to be patient and wait it out. Hopefully not to much longer though.

Thanks

[Shifty]

@markphin: I am about 5 weeks post a re-plaster with krystalkrete. For the first 3-4 weeks, I was adding a similar amount of muriatic acid as you were. I was brushing the surface twice a day; however, a lot of the plaster dust was staying in the deep end near the main drain. Once I hit the 30 day mark and used my pool vac, I was able to vacuum any excess plaster dust. Since removing the plaster dust, the pH has stabilized. While the plaster continues to cure over the next 6 months, I still expect the pH to slightly fluctuate.

Make sure to test your water regularly.

Have you seen your pH stabilize? I realize this thread is almost a year old.