How to stabilize my PH

[ljt014]

We are new pool owners and new to this Forum. We have a 16,500 I/G gunite SWG pool. The Filter is a Jandy CL460 Cartridge Filter and we have a Aquapure Ozone Generator. The salt was added a little over a week ago. My current test results are;
FC – 4
TC – 4
ALK – 90
PH – 7.4
CYA – 30
PHO – 100
CAL - 150

We have dark grey plaster and have recently been noticing the plaster was lighter in color in numerous places, mainly in the deep end. We brought it to our Pool Builders attention and he had the Plaster people come out. They told us that it was from what they called White Scale. They told us to keep the PH at 7.2 and it should clear up in a week or so. I have been doing my best to keep the PH at 7.2 but it is all over the place. I have added almost 2 gallons of acid in the last week and have had a PH reading as high as 8.0. I have a Taylor K2005 test kit and have been testing the PH daily and everything else 2/3 times a week. Do I need to add CYA to keep the PH more stable? If so how much? Also what is White Scale? And is lowering the PH the way to correct it?

[Watermom]

I'm going to ask Ben to take a look at your post and see if he can offer some advice.

[PoolDoc]

As far as I know "White Scale" is a term with no particular meaning, except the obvious one.

I'm *not* a plaster expert, but I know there have been problems with colored plaster almost as long as there has been colored plaster. And, if there's ever been any agreement on what the causes were, I haven't heard about it. All I've seen are these circular accusations: "It's the colorant! No, it's the cement! No, it's the plasterer! No, it's the homeowner!", and so on.

Blaming the homeowner - which might be valid, but I don't know - is popular, since they aren't in the trade.

Bottom line: do what he says, no matter how much acid it takes, so you'll be able to blame him.

Oh yea, CYA will not help stabilize pH.

Good luck!

[waterbear]

Oh yea, CYA will not help stabilize pH.

Good luck!

This is a salt pool so having the CYA higher WILL lead to better pH stability because there will be less ougassing of CO2 because of less cell on time. 30 ppm is too low for a salt pool.

Also, dropping the ALK to 70 ppm will also help. However, it will get there on it's own fairly soon if you keep the pH at 7.2 for a while to dissolve the scale deposits.

[waterbear]

we have a Aquapure Ozone Generator

I believe you mean Aquapure Chlorine generator!
There is an ozone generator names UltraPure but it is not made by Jandy/Zodiac

[ljt014]

I added 4lbs of CYA last Friday and have kept the pump running through this morning. I expect that the 4lbs of CYA will bring it up to about 45PPM but I did not want to add too much because I am aware of the issues if you get too much. If I understand it right 4lb of CYA will raise the levels 30PPM in 10,000 gal. I suspect that I will need to add another aproxamentally 4lb to bring the level up to 60PPM. Am I thinking right? I have also reduced the Salt generator from 70% to 60%. I was planning to test again tonight but we have finally gotten some rain so I imagine that levels are off a little at this point. As far as following what the Plaster Company has recommended that is exactly what I am continuing to do so that they cannot put it back on us. Will bringing the PH and ALK down remove the scale as they have said? This site is awesome, I have learned a lot from reading all of your posts. Thank you all very much.

[waterbear]

Bring your CYA up to the maximum, which for your Jandy unit is 75 ppm (and given the amount of precision in the CYA test I would suggest brining it up to 80 ppm).
Drop your TA to 70-80 ppm (70 ppm is better). (Lower TA means slower pH rise from outgassing of CO2)
Once this is done adjust the FC level in the pool to 4-5 ppm by adjusting cell output and/or pump run time.
Maintain your pH at 7.6 and not lower (the lower you put the pH the faster it rises) and drop it back to 7.6 when it climbs over 7.8.

Finally, consider adding borates to 50 ppm since this will introduce a secondary borate/boric acid pH buffer system that will work in compliment to the bicarbonate/carbonic acid buffer system we call TA and will maintain the pH around 7.6-7.7 for much longer than without the borates.