Since borates added, pH stays high

[257WbyMag]

Since I added borates to 50 ppm, I have noticed that my pH continues to climb from 7.5 (where I like it) to 7.8 despite my attempts to correct it with HCl. Now, I know that 7.8 is okay but this is the high end of acceptable and leaves no safety margin. Because I keep such close eyes on my numbers, I have not seen it go higher than 7.8 because I always intervene with HCl. Yet, despite my efforts, it continues to creep up every time. Maybe I just don't understand this secondary buffer system of borates quite so clearly but I assumed that I would have more stability in pH fluctuation in my water with borates. Yet it seems that I am no better off now than I was before adding borates as I am still using the same amount of HCl that I was before and perhaps, even more so. I wonder, if I were to leave it alone, would the pH would continue to climb to 8.0 or above or if it will stay at 7.8? No aeration is being performed at this time. Straight up BBB all the way.

Latest numbers:

FC 5.2 ppm
CC 0 ppm
TC 5.2 ppm
pH 7.6
TA 80 ppm
CYA 50 ppm
CH 410 ppm
borate 50 ppm
ambient temp 85 degrees F
pool water temp 78 degrees F

 

[JasonLion]

Borates buffer PH changes, they don't prevent PH changes. The PH will continue to rise, just more slowly than it would otherwise. To stop PH rise you need to lower TA and allow PH to go up a little higher than you might otherwise. You might try lowering TA to the 50 to 60 range and seeing if you can get PH to settle around 7.7.

Note: if your plaster is less than one year old the PH will rise regardless of TA. Borates will still slow the rate of increase.

 

[257WbyMag]

That's pretty much what I was thinking. I'll keep adding acid until the TA is a little lower and see if that helps.

I am a little surprised that the pH has continued to rise at the rate that it has though. I didn't expect it to lock in place anywhere but I did expect the rise to be somewhat slower.

 

[Guest]

How new is your plaster?
Also, try keeping the pH AT 7.6 and when it hit's 7.8 add acid to lower it to 7.6 and not lower. Also, if your waterfall is running that is going to cause a pH rise due to aeration.

 

[257WbyMag]

How new is your plaster?
Also, try keeping the pH AT 7.6 and when it hit's 7.8 add acid to lower it to 7.6 and not lower. Also, if your waterfall is running that is going to cause a pH rise due to aeration.

The plaster is 8 years old and the waterfall has not been running.

Alright, I'll keep it around 7.6. Thanks!

 

[Guest]

Then just keep your pH between 7.6 and 7.8. Don't worry if your pH stays at 7.7. That is usually where it will stabilize. Lowering your TA a bit more should help.