pH Question

[ThomasG]

Pool plaster surface is about 4 months old. Once I started testing the water myself with a Taylor K-2006, I started working TA down from a high of 130 to where it is today. CYA after the pool was turned over to me was 60, and CH was 200. Torrential rains over three weeks in July pretty much did a number on my pool chemicals, but after 12 pounds of calcium chloride and several additions of CYA, I have finally got them all adjusted (I wish my rain making procedure--adding CYA--would work for folks in the drought-stricken west). My CH could probably be a little higher, but I'm waiting for another month or month and a half for the likelihood of more torrential rains to decrease.

I understand that with new plaster pH is likely to tend upwards, as it also is with a SWG. I find myself adding anywhere from 8 to 14 ounces of muriatic acid every other day to keep pH in check. Just wondering if this is out of the ordinary.

Test results:
FC; 5.5
CC: 0
pH: 7.8
CYA: 70
TA: 70
CH: 290
Salt: 3400
CSI: -0.12

 

[YippeeSkippy]

Your pool is probably still in curing mode so I wouldn't worry yet. Do you have water features such as fountains, overflows or jets which all cause aeration and pH rise?

I don't see the most current CYA reading, but if your CYA is still 60 as it was before all the rains, your FC level is too low. Careful with that or you'll be dealing with algae soon. Please refer to this- Pool School - Chlorine / CYA Chart

 

[JoyfulNoise]

With an SWG you want to target a higher CYA level, 70-90ppm range. The higher CYA levels allows you to run the SWG a little less but does require you to have a higher minimum. Your pH rise is not unusual given your pool (new plaster and SWG). It should get better over time but we're talking 12-18 month time frame. You could try lowering your TA a bit more to maybe 50-60ppm but you'd have to target a higher pH (min of 7.6) and a higher CH in order to keep your CSI in a range that will reasonably protect your plaster (-0.2 <CSI< 0). If you do all that and you still find the acid demand to be too much, then you can try 50ppm borates to act as additional pH buffer.

 

[ThomasG]

Oops, forgot to include CYA. It's there now--70.

- - - Updated - - -

Your pool is probably still in curing mode so I wouldn't worry yet. Do you have water features such as fountains, overflows or jets which all cause aeration and pH rise?

I don't see the most current CYA reading, but if your CYA is still 60 as it was before all the rains, your FC level is too low. Careful with that or you'll be dealing with algae soon. Please refer to this- Pool School - Chlorine / CYA Chart

Thanks for the reply. FC seems just fine, according to the chart, for CYA of 60 or 70, where it is.

Edit: didn't realize sig was not showing, so you may have missed the SWG.

 

[YippeeSkippy]

Ah yes, didn't have that important detail