I'd like some advice on whether or not these numbers are ok to close the pool with

[three4rd]

Hi,

I have the following -



TA - 85
CH - 220
pH - 7.4
SI - -0.40

The plaster is only a few months old, and so the pattern has been that the pH continues to go up. From frequent additions of dry acid over the past few months, the TA was knocked down to around 60, a bit low, and so I brought that up to over 80. My most recent addition of dry acid took the pH down to 7.4, which is where it is at now. However, I can only presume that it will continue to rise. Should I bring up the pH a bit? Or leave as is and close it up. I will recheck in a few weeks to see how things are going as per the recommendation of my plasterer, since his thinking is that if the pool is ever going to scale it'll be during this first winter with the new plaster. Any help or advice appreciated.

Thanks.

 

[JasonLion]

You are fine continuing like that. Long term you are going to want to raise the CH level a little, as you are a bit below our recommended CH range (250-350). However, it might be best to leave Ch alone until next spring. Having PH and CH a little low (i.e. where they are now) going into your first winter is a good idea.

 

[three4rd]

So you don't think I have to worry about etching by closing with a pH of 7.4? I can't imagine that the pH will stay down there for very long.

 

[JasonLion]

No, there shouldn't be any etching unless SI goes down to -0.6 or lower. Keeping SI fairly low gives you more headroom for PH to go up before there could be a scaling problem.

To minimize scaling risk over the winter you should close as late in the season as practical and open early next spring. The colder the water is, the less the PH will go up. After this winter this won't be an issue again, as the plaster should be done curing after one year.

 

[three4rd]

OK...thanks so much. The water is now 61 degrees, and it is definitely later in the season than usual for when I typically close, but I read here that it's good to wait until the water is around 60 since there is less chance of algae developing. I do plan to open earlier next spring as you recommended. I can live with a scale issue, but etching is far worse. I think I'll proceed with lowering the water level now and get everything closed up, then recheck in a week or so and see where the numbers are at. I appreciate your help.