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It's pretty darn close to 7.2 today, and TA measures closer to 80 whereas 2 days ago it measured closer to 70. I'll check it in another couple of days to see if we're up to 7.4. The chlorine is a bit high (3-4 ppm) so I've reduced my generator to 60% (from 80) -- other than that, I'll make no changes.

No one seems to want to answer my question about whether it's possible to reduce TH with a sequestering agent...? :-/

Mike

I do not believe it is possible, or at least feasible, to reduce the TH.

With your TA at 80, or close to that, the pH should become fairly stable. If it stabilizes at anywhere from 7.2 - 7.6 why mess with it?

Yes, Th can be reduce, but anyone in their right mind would not be wise to tell you how...

Because one little missed application would make a real mess that would be very hard to clean up...

Bill Tech II

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Bill Tech II

Hard water can be softened by passing it over an ion exchange resin. The ion exchange resins are complex sodium salts.

Water flows over the resin surface, dissolving the sodium. The calcium, magnesium, and other cations precipitate onto the resin surface.

Thanks for the info regarding reducing TH.. I'm not sure how exactly an ion exchange resin would be used for pool water, so I'll leave that alone. Here's what my water's done in the past week:

DATE	pH	TA
05/30/06	6.8	70
05/31/06	7.0
06/01/06	7.2	80
06/04/06	7.6	90-100

You can see that both the pH and TA are rising, this is without adding anything to the pool (other than letting the chlorine generator do its thing). At this rate I'd have to add the recommended maximum amount of acid (1 qt in 20,000 gallons) every single day in order to keep the pH stable.

Knock the TA down again. When it stabilizes, so will pH. (Please excuse me if I sound like I know what I'm talking about).

I appreciate any advice I can get! This last time was the third time I've used gobs of acid to reduce the TA to 80 or below, and every time both it and the pH come back up. To what value do you suggest I reduce the TA? How do I get it to stay there?? Thanks...

Is this a plaster pool, and if so, how old is it?

Sorry, after I submitted my post I thought I should have refreshed the stats. It's a 30 year old plaster pool that was replastered and retiled in 2003. It's 22,000 gallons including the built-in spa. The filtration pump and spa air pump were new in 2003, as was AquaRite salt system. I believe I installed the 53 sq. ft. DE filter in 2002. The heater is an old (20 years?) Raypak. I'm in Southern California where the water is very hard and the heat regularly hits 3 digits in the summer (lots o' evaporation, which explains my TH I'm sure).

Does that cover it?

In a plaster pool, You will notice a pH creep no matter what you do.. Your TA could be Zero and the pH will still be high.

Ironically this pool did NOT creep before I had it replastered.. in fact I occasionally had to add soda ash!

A little creep doesn't bother me. Buying 2 gallons of acid per week for 20,000 gallons DOES bother me. Doesn't that seem like a lot?

When my pool was new it took about 4 years before I had to stop putting acid in once a week. I was using about 2 gal/month for the first two years and the about 1 gal/month for the remaining two. Now I use about 1 gal/6 months (i.e. the swim season for me) and the pool is 8 years old.

I have a 23K gal pool with a diamond brite finish and use trichlor.

Mike

A freshly plastered pool WILL use acid, lots of it, for a while. After many years it will become neutral and finally you will be adding Soda Ash. Then you know its time to refinish it. Hopefully this will be about 20 years :) Using a low pH form of chlorine will help. Using as little as possible of liquid chlorine will help and that requires some proper, but easy maintenance. IE: Controlling combines and organics. (hint: Ozone, Oxone, Enzymes) If your TA is within 80-120 go back to bed and don't worry about it, it's good. Don't let the hardness get away on ya tho, but if your fill water is typically very high you will have issues to deal with. Thats the issue though, not lowering everything else to balance it. Hard water probably means you have a softener anyways so this should prompt you even further to not waste water in the pool.