Auto Pilot Total Control, PH always needs to be increased.

[waterbear]

Hi Ben,

The pool manufacturer is puzzled because he says that normally pH will always drift up and not down. He said it had something to do with the "leaching" of the marcite.

Nope! The manufacturer is feeding you a line because he does not have an answer for you! pH rise in a salt pool, whether it is plaster, paint, vinyl, tile, or fiberglass is PRIMAIRLY from outgassing of CO2. Primary water balance parameter that affects outgassing of CO2 is TA followed by pH and (with a salt pool, CYA since it has an effect on cell run time and therefore aeration of the water, which speeds up outgassing). My question is what is your TA? If your TA is low and your pH is low then raisin the TA could help (assuming that NO acid is being introduced into the pool, as Ben suggested above and that the plaster finish is fully cured and not introducing alkaline material from curing plaster).

FWIW, I have a fiberglass pool with a SWCG and it has a tendency for pH to rise and I have seen just as many fiberglass and vinyl pools with rising pH problems when SWCGs are used. Curing plaster can add to the problem but they are NOT the acutual primary cause of pH rise!

Are you manually testing pH or relying on the sensor? pH sensors do wear out and need to be replaced peridociacally and if they are allowed to dry out can be permanently ruined (such as when the pool was being refinished perhaps?). 4 years certainly is long for the life of a pH electrode!

Post a full set of test results done with a good test kit like a Taylor K-2005/6, TF-100, or PS-232,233,234 and we can take it from there.

[PoolDoc]

DWM;

If you were my local customer, and I was visiting, I would say "Hm-m-mh, let me take a look." and then proceed to verify everything you've told me. I can't do that.

So let me suggest that YOU do what I'd do next, if I were there.

I'd disconnect 100% of your SWCG and feed system (and make 100% sure you couldn't turn it back on behind my back -- been there, got blamed for the "inexplicable" problems, NO thanks), and then have you run with bleach for 2 weeks, and see what happens.

ALSO . . . I'd test your water, and especially your TA / CA with my OWN Taylor based kit. And THEN, I'd test your fill water.

But, since I'm not there, I can't do that. But it's what I recommend to you. You'll need a Taylor K2006 -- Amazon links in my signature.