Long Hot Summer and Pool

[PoolDoc]

Hi Dallas;

You have to keep your pH down, no matter how much muriatic it takes. I can't estimate what the results of your plaster curing will be, but I can tell you you'll have to use as much acid as it takes. So long as you are not adding soda ash or sodium bicarbonate . . . there's not much else you can do. Hard water -- like your fill water -- is often also high in carbonate alkalinity, so that may also be a source of your pH rise. But, when water evaporates, you have to replace it. So it all comes back to, "Add enough acid to get the job done, however much that it!"

High water temperatures definitely seem to make things harder and there's not much you can do about that, either.

But, you DO want to increase your chlorine levels, or you WILL likely have algae problems. Check the Best Guess chart (links in my sig!) for correct chlorine levels with a CYA = 100.

[DallasVal]

Thanks for the quick response, Ben. I do understand I need to get the chlorine levels up with the CYA so high and have been referencing the Best Guess chart. Hence, the trip for bleach. Should be up to par again by tomorrow morning. At least the water has been solidly crystal clear for the last 2 months, with no algae, even in this heat. But regarding the pH.....I get that I have to keep it down. My question - is 7.8 OK, or do I need to keep it at 7.6, regardless of constant acid demand? I do realize my LSI is high right now, with scale a threat, which is one of the last things I want. It's just that the pool seems to want to stay at 7.8.

The site is such a help. Thanks for keeping us straight!

[PoolDoc]

If it's actually 7.8, and not "at the top of my test kit scale which is 7.8" . . . you'd be OK. The problem is, if it's at the top of your kit's scale, then 7.8 REALLY means 7.8 or higher, not 7.8 actually.

However, given the high CH, you probably need to hold a pH of 7.2 for awhile in order to lower your TA, which drops when you hold your pH low AND aerate. (Lower pH turns some of the TA into carbon dioxide, when then leaves the pool slowly without aeration or more rapidly with it.)

[DallasVal]

It is actually 7.8 - test kit goes to 8.2 and the colors are noticeably different. The spa has a fountain and water circulation is shared (common pump), so it aerates. I'll take your advice and drop the pH for a while to see what happens. As I read your response, I also need to keep TA lower (which will happen as a result of pH going down with muriatic acid added). It had been hovering in the 80 - 90 range in the beginning. Back then, when I took the water to the pool store to have it tested as verification of my tests, the guy was adamant that I needed to get TA up to 100 - 125.

Thanks again.