Wild swings in PH on new pool, Diamond Brite

[susa]

am currently on day # 13/14 since starting fillup of new pool, Diamond Brite surface.

was given directions to keep PH at 7.0 for 30 days as ..."...it will help the surface to cure hard... brush daily..."

pool was acid washed before fillup and I ran old system (old pump, old filter) for about 10 days to collect most of the dust that brushing caused to flow into the lines.

PH is daily easily over 8.0, add 1 gallon muriatic acid and it's down to 6.8 - 7.0, is this quite normal for a new surface ?

new system is now running 24 hours/day, pump is set to 122 watts, 15 GPM and circulates water

have added just liquid chlorine and muriatic acid, nothing else but I do have on hand baking soda, borax and cyanuric acid and of course salt (..but salt will have to wait until January..)

 

[dmanb2b]

A full set of test result would help narrow things down, but it is perfectly normal to experience frequent PH rise while the plaster cures. It will get worse once you kick the SWG into action, but eventually the plaster will cure and your TA will drop down to a level, which will stabilize PH.

 

[susa]

this morning

PH 6.6
TA 30

I added one 72oz/4 lbs box of Borax which brought PH up to 7.2

Since TA was low, added baking soda and measured couple hours later at 60, will wait until tomorrow to make any changes while system continues to run (pump on 24hr/day)

 

[Bama Rambler]

Which test kit are you using?

With a TA of 30 your pH is going to have a tendency to swing wildly. You did the right thing by bringing it back up a little.

 

[bk406]

As an FYI, when both the pH and TA are on the low side, you can use washing soda instead of borax to raise the pH. Normally, we suggest Borax to raise the pH since it doesnt have much of an effect, if any, on TA. And most of the time you want to increase the pH but leave the TA alone. In Susa's case, adding ~3 pounds of washing soda will raise the pH to the same 7.2, but also raise the TA by 20 ppm as well.

 

[susa]

now, 8 hours later, after my initial mixing and adding, Leslie's tests:

Water Temp:72 F
CH: high
Phosphates: 0.5
TA: 70
PH: 7.0 (this is actually where I want it to be!)

No cyanuric acid, which I am aware of and will slowly be adding.

Have only used liquid chlorine last 14 days, slowly adding muriatic acid to keep PH and now this is the first time that Alkalinity is almost where I want it, will add a little Sodium Bicarb tomorrow to bring it to 80-90.