New Pool - rising PH...should I add Borates?

[mxfan]

Topic Split off by Moderator

I recently had our pool re-done completely. It is a sculpted cement pool (looks like natural rock) and also re-did the floor of the pool also with a plaster similar to pebbletec.
The remodel was completed about 3 months ago and I also converted to a SWG at that time.
current levels:
FC 5
CC 5
PH 7.7
TA 80
CH 300
CYA 80
temp. 82

I read the pool school and followed the SWG section and have the levels all at the recommended levels. However I have been adding acid daily because the PH constantly rises. I add about 15 - 20 oz. daily to keep the PH in the 7.6 range.
The water is clear and I have no other issues, but I like the idea of adding Borates if it will help stabilize the PH level.

My concern is will the high level of acid (while adding borax) have any possible affect on the surface of the pool. Again it is sculpted cement that is stained for the final rock look.
Thank you.

 

[frustratedpoolmom]

It is normal for the PH to rise while the surface cures - this can happen for up to one year so don't be too concerned, just maintain the level with acid as you have been doing.

No, if you follow the steps for adding Borates it shouldn't have any adverse affect on the pool. I'm not sure tho how much the borates would slow the ph rise from curing plaster...

Remember to add chems carefully with the pump running, pouring slowly in front of the return flow into the water.

 

[lbridges]

My pool is about three months old now. At six weeks I added borax to approx 50ppm (12 boxes) IAW the TFP directions found here. I saw no damage to the pool or staining.

I had/have rising pH problems due to the new pool - both before & after borax. Borax inhibits the pH rise some (no scientific measurements taken) but it also seems to inhibit the lowering too - so while I don't add as often, I have to add more when I do - works out to be the same amount of MA.

Hopefully that made sense.

 

[Melt In The Sun]

You could also lower it to 7.2 or so each time, then you shouldn't have to add it quite as often. It will still turn out to be the same amount though.

 

[mxfan]

Thanks for the replies!
I think for now I will hold off on the borates and just keep maintaining the rising PH with the daily dose of acid.

I liked the idea of the borates for a more controlled PH and also improved clarity in the water...but I will let the new plaster cure and possibly look at adding borates next season.

Thanks again!
...Eric

 

[JamesW]

I recently had our pool re-done completely. It is a sculpted cement pool (looks like natural rock) and also re-did the floor of the pool also with a plaster similar to pebbletec.
The remodel was completed about 3 months ago and I also converted to a SWG at that time.
current levels:
FC 5
CC 5
PH 7.7
TA 80
CH 300
CYA 80
temp. 82

I read the pool school and followed the SWG section and have the levels all at the recommended levels. However I have been adding acid daily because the PH constantly rises. I add about 15 - 20 oz. daily to keep the PH in the 7.6 range.
The water is clear and I have no other issues, but I like the idea of adding Borates if it will help stabilize the PH level.

My concern is will the high level of acid (while adding borax) have any possible affect on the surface of the pool. Again it is sculpted cement that is stained for the final rock look.
Thank you.

You could use boric acid instead of Borax to add borates. Using boric acid is mostly pH neutral. For your pool, you would need 53 pounds of boric acid. Borates are especially helpful in a plaster pool that also has a SWG.

Allowing the pH to stay closer to 7.8 will help reduce pH rise (because it reduces the level of carbon dioxide in the water). A higher pH won't cause any scale as long as the CSI does not go too high. You can use the pool calculator to calculate your CSI.

Based on the following numbers:

pH = 7.8
TA = 80
Calcium Hardness = 300
Cyanuric acid = 80
Salt = 3,000
Temperature = 82

Your CSI would be -0.08, which is a good target for a plaster pool with a SWG.

Based on the following numbers:

pH = 7.8
TA = 90
Calcium Hardness = 300
Cyanuric acid = 80
Salt = 3,000
Borate = 50
Temperature = 82 F

Your CSI would still be -0.08. For plaster, you want the CSI as close as possible to 0.0 without causing scale in the cell.

 

[257WbyMag]

It's not how much acid that you are adding that could be detrimental to the surfaces of your pool, but the pH itself. Curing plaster will always result in an increasd pH. With an SWCG, you have even more of a pH rise to deal with. It is just going to require more acid more often. I would shoot for 7.2 each time you add acid. Adding borates is something that I would suggest after the plaster has cured but I don't think that it really would help you much before this process has taken place.

 

[JamesW]

I would shoot for 7.2 each time you add acid.

The problem with lowering the pH to 7.2 is that it will create much more carbon dioxide and it will cause more plaster to dissolve. Both of these things will significantly increase pH rise and total acid demand. By maintaining a pH closer to 7.8, the amount of acid needed will be much less.

Adding borates is something that I would suggest after the plaster has cured but I don't think that it really would help you much before this process has taken place.

50 ppm borates have the same pH buffering capacity on the upside as 221.6 ppm of TA have at buffering the pH on the downside. This will allow the CSI to be higher for the same scaling risk in the cell. A CSI closer to 0.0 will reduce pH rise from new plaster.

 

[JasonLion]

You shouldn't add borates in the first 30 days after fresh plaster is applied. Other than that it is a great idea and will help.

When dealing with either PH rise due to curing plaster or very high TA levels it is best to lower the PH to 7.2 each time. That gives you more time between acid additions and will not have any negative impact on the plaster nor will it cause any meaningful amount more total PH increase. Lowering PH to only 7.5 or 7.6 is important when you are aiming for a steady state with relatively low TA and no plaster curing issues.