Dropping TA, for the workin man or woman....

[dhanger]

This "rising pH" seems to be a theme lately, there's a couple other threads discussing it. The one with chemgeek and pooldoc discussing higher level chemistry is interesting to me but over my head right now, but it sounded like chemgeek was suggesting that pH looks for it's own plateau based on some other factors, including a TA lower than 80.

This is the first year (in 5) that I've paid close attention to my water balance, and have the same issue of rising pH. Lately I've been adding acid nearly every other day to counter it, but I'm tempted to leave it alone for a few days to see if it does level off. I haven't recorded a level above 7.8 yet, but that's because I haven't allowed it any higher. Steve, sounds like you're saying that the high TA was the problem, and you've stabilized it now with lowering the TA. My TA has been floating around 80-90 since I started checking about 3-4 weeks ago, but the pH still rises relentlessly. I'm really scratching my head at this point.

On a related note, since my pH does rise, and I haven't kept a close eye on it for a long time and it probably got way out of control at times, the pool calculator says that (given higher CH levels in Arizona) the SI rises with it, which probably explains why my pool developed such a thick calcium ring within the first two years. It got so out of control without me realizing it, that by the time I tried to do something with it, it was beyond my puny efforts. I've just let it be for the last couple years, but a few days ago, while in the pool, I noticed that the ring on the tile portion was starting to disintegrate on its own. I tried some pumice on it, and with a little elbow grease the rest of it came off, which didn't work at all in the past. My only thoughts are that keeping the pH in balance better is having an effect on the existing ring. Well, that and having drained and refilled completely last May, which lowered the CH considerably (in fact I had to add calcium to raise it to it's current level of 190). Don't know if I'm interpreting all this correctly.

Dan

[CarlD]

Dan,
Do you have a SWCG system? They are known for raising pH. Plus you have a concrete pool--have you been keeping your calcium levels correct?

With a concrete pool we still are not convinced that lower TA levels as a good idea. The chem guys have to figure in the calcium, calcium carbonate, leeching, etc.

Carl

[dhanger]

No, I don't have a SWCG, just using bleach or LC now. Up until I hit this forum (about 4 weeks ago) and converted, I was using a Pool Frog inline chlorinator, which used tri-chlor cartridges (and would raise the acid level as I understand), but I don't use that anymore.

Regarding calcium, here's what I wrote in the previous post-

drained and refilled completely last May, which lowered the CH considerably (in fact I had to add calcium to raise it to it's current level of 190)

Prior to that, I don't know what the CH level was, as I never tracked it

So, would you say that I should keep my TA level at it's current 80 or higher? That would make sense to me for concrete, as you say.

Dan

[steveinaz]

Dan
I don't know about your fill water, but here in Sierra Vista the fill water TA is 170ppm--I'm sure this contributes to the rising pH problem around here. All of our friends with pools also battle rising pH on a constant basis.

[dhanger]

I just checked, the fill water TA is 90, and the CH is 80.

When I first started testing my water, about 4 weeks ago, the TA was low, don't remember how low, but it was lower than the recommended 80-120 for concrete/plaster, so I added enough baking soda to bring it up to 100. The next test was at 90, and yesterday it was at 80. So if alkalinity is dropping, acidity should be rising, which means pH should be going down rather than up, right? And yet it goes up. There must be something wrong in my reasoning here, hopefully the experts can straighten me out.

Clearly, though, I have an issue with the TA dropping, which must mean I have some unwanted aeration going on. I never use the waterfall, the returns are down or sideways and never break the surface, about two weeks ago I disconnected the ozonator which I determined was a suction side device and PoolDoc suggested could be aerating, the only thing left that I can think of is my in-floor popups, which when I use them, definitely ripples the surface a lot in the shallow end. Until a couple weeks ago I was running that every night, but I've stopped that practice just to see what effect it would have on the cleanliness of the pool, and to conserve electricity. So I think I'll add some more baking soda and keep testing to see if that makes a difference, and just use the popups when the floor is actually dirty!

[chem geek]

You are most definitely going to need to get your Calcium Hardness (CH) higher. You can use The Pool Calculator to calculate the saturation index which you want closer to zero. If it's too negative, then your pool surface will have a tendency to dissolve into the water; if it's too positive, then there will be a tendency for scaling to occur.

[dhanger]

Yeah, I've already done that, I was just reporting the fill water numbers. Currently the pool is at 190.

Dan