Test Check

[jhm]

Thanks for all the advice. It sounds like I need to work on the TA by lowering pH to around 7.0 for a while. Aeration shouldn't be a problem as we have these things on a couple of returns called Baja Bubblers, giving a fountain type effect. Hmm...maybe those might contribute to my continually rising pH?

Does high pH have any effect on chlorine consumption?

Thanks,

Jim

[szampino]

I kept meaning to ask you if you had some kind of Water Feature in your pool. I used have a fountain and couldn't understand why my PH kept rising. Sounds like you know have a plan.

Good luck.

[CarlD]

Thanks for all the advice. It sounds like I need to work on the TA by lowering pH to around 7.0 for a while. Aeration shouldn't be a problem as we have these things on a couple of returns called Baja Bubblers, giving a fountain type effect. Hmm...maybe those might contribute to my continually rising pH?

Yup. Turn them off for a week and see what happens! Bet pH is far more stable.

Does high pH have any effect on chlorine consumption?

Thanks,

Jim

I don't think it does, (the chem gurus can chime in) but it DOES have an effect on the effectiveness of chlorine...the lower the pH the more effective the chlorine is. But at super-effective levels, your water will be acid enough to melt vinyl (which you don't have).

I tend to prefer pH in the 7.3-7.5 range for just hat reason. Chem_Geek has tables on that --if you dig around you may find them.

[chem geek]

The graphs of chlorine effectiveness vs. pH with and without CYA are in this post. The bottom line is that with CYA in the water, it acts to buffer the disinfecting form of chlorine which means the disinfection rate doesn't change that much with pH. Without CYA, going from a pH of 7.5 to 8.0 drops the chlorine effectiveness by around 50% while with CYA it only drops around 15% Of course, without CYA, the chlorine effectiveness is huge so even a drop of 50% isn't a big deal (it's still over a factor of 15 higher at the same FC level when the CYA is 30 ppm).

There is a theoretical increase in the breakdown of chlorine from sunlight at higher pH since hypochlorite ion breaks down about 6 times faster than hypochlorous acid from the UV in sunlight. Though the disinfecting chlorine (hypochlorous acid) doesn't drop much at higher pH, the hypochlorite ion increases a lot to compensate. With an FC of 3.5 and a CYA of 30 ppm, going from a pH of 7.5 to 8.0, the rate of chlorine loss from sunlight is almost tripled. However, we've never done any experiments with real pools to see if this "theory" actually happens in practice. There have been a couple of anecdotal reports indicating that some effect of this sort does occur. Just remember that chlorine loss has multiple sources and we're only talking about the loss due to sunlight in this discussion.

Richard