I usually test on Saturdays and find that the pH is 7.8 - 8.

[Brentr]

Split off of this topic. JasonLion

I am curious to know also because we are in the same boat. I usually test on Saturdays and find that the pH is 7.8 - 8.2. I add muriatic acid to bring pH to 7.2. Sorry to ask this question to the OP, but what would happen if I left the pH high? I have never went 2 weeks without testing.

 

[Brentr]

Re: Pebble pools tend to require more acid than plaster pools

Pebble surfaces are less reactive than plaster surfaces and should react something like a pool that was 7/8 vinyl and 1/8 plaster.

I suspect it has to do with the kind of equipment purchased with a pebble pool, rather than anything inherent to the pebble surface. Pebble pool owners are more likely to purchase a SWG, more likely to have water features to cause aeration, etc just because they are spending more money.

Leaving the PH high gives you significantly higher risk for calcium scaling and metal stains, depending on your chemical levels in the water.

PH drift can be minimized by lowering TA to around 60, or better still adding borates to around 30 to 50 and then lowering TA to around 50.

Not to rain in on the OP, but this is related so please excuse me.
Jason here are my numbers as of 08-01-10
FC - 5
CC - 0.5
TC - 5.5
pH - 7.2 Added MA 24 hrs previous day because pH was 7.8 - 8.2
T/A - 40
CH - 450
CYA - 45
Temp - 90
SWG - 3100
Borates - color is between 50 - 80 ( I find it hard to distinguish colors using Lamotte strips)
It seems to me that I still got the same swings in pH as before adding borates which I did on 02-07-10.
We only aereate on the weekends , maybe a few hrs at most

 

[JasonLion]

Is the pool less than one year old? Plaster/pebble applied in the last year will cause the PH to rise constantly. There is a dramatic PH increase during the first three or four weeks, and then a slower increase for up to a year.

You should raise your CYA level up to between 70 and 80. That will help stabilize the PH some.

How often/long do you run the sheer descents?

 

[Brentr]

Jason, the pool is exactly 1 yr old. Ouch I did not catch my CYA being so low. I will adjust tomorrow back to 70-80. I also run the sheer descents about a couple of hrs on the weekends. Thanks