Cant keep pH down

[adeleincali]

Yesterday morning, numbers were as follows:

FC 8
CC 0
pH 8++
TA 125
CH 250
CYA 70

So, I dumped my 4th gallons of Muratic Acid in. The first 2 gallons over the past 3 weeks were from my sister and probably not the freshest. The 2nd 2 gallons I have put in the past week or so, were fresh, from the Pool Store and the highest potency.

After an hour of putting in the MA, I tested at 7.6.

This morning I test, OVER 8 AGAIN!!!

What is up?????

 

[AimeeH]

You may find that lowering your TA will help stabilize the PH. Try lowering closer to 70.

Pool School - Lower Total Alkalinity

 

[Richard320]

It's the high TA and the constant aeration from running the spa waterfall all day that drives the pH up.

Your pool is huge, so it's going to take a lot of acid to lower the TA to the 60-70 range where the pH rise will slow down. And of course, every time you add topoff water, you'll raise TA again. Every time I add a couple inches of water I have to add a quart of acid and my pool is half the size of yours and my TA is already at 60.

 

[zea3]

Do you run the spillover from the spa whenever the pump is on? If so it is aerating the pool and that will drive the pH up. Try lowering the TA to 70 with MA and not running the spillover as often.

 

[YippeeSkippy]

Also, to add to what AimeeH said, your spa spillover might be contributing to your ever rising pH. Can you limit the spillover action to just a few minutes a day? You might see marked improvement.

Make sure you're buying 30% MA. Some stores sell "low fumes, half strength" MA and folks don't realize that they're paying the same for weaker stuff. You'd have to use double the amount to get the same response you seek. Look at Lowes in the paint section for full strength stuff.

Maddie

 

[Meadow]

to the OP.... fyi, our city water has TA of 125 and CH 175 when I tested last. Coupled that with our current weather condition, our pool water evaporates a lot requiring frequent refills.
You need to bring your TA down to 50 or 60 ppm using the aeration method as posted above. Doing so will slow down the PH rising and therefore, reduce MA consumption.

And as mentioned above, make sure you use the full strength MA (31.45%).