How can I lower my TA to 80 without also dropping the pH down into the acid range?

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Hi Sunny,

Thanks for the reassurance. I certainly FEEL like a new pool owner, even though I've had the pool for 25 years. Well, with the reno it is basically a new pool. LOL about your 'raised wall with the crack'.

I was wondering though if my hardness level should be brought back up a bit. The fresh fill tested at 199, and now it is at 165. I know that if I take a water test to my pool store they will want to bring the CH up to at least 200. If I plug that number into the calculator with everything else remaining unchanged, it drops the CSI even lower to -.0.2. I'm not sure that would be the best thing.

What I DO think I need to do is get IN THE POOL more and simply enjoy how the new tiles, coping, and plaster look. I've been too preoccupied with water testing, adding dry acid, and brushing. Like you said, time to chill a bit with the water chemistry! Up until now I've always just relied on the pool store to tell me what to add, and really paid little attention to how the various parameters interrelate, let alone have any interest in SI. But from what I've been reading here, and from my plasterer's advice, I can test as accurately as the pool store with the kit that I have.

Many thanks.
 
How can I lower my TA to 80 without also dropping the pH down into the acid r...

And considering what little real water chemistry knowledge the pimple-faced clerk behind the counter has, imagine how scary it is to think of all the junk you were adding!

Get out the floaty, crack a can of beer (if that's your "adult beverage" of choice) and relax in the water that you know is properly cared for....but no pee'ing in the pool or else we'll know it from your test result :p


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Then again, following my store's advice of chemical treatment did keep things in pretty good shape the way it would seem - original plaster lasted 25 years - not bad! I think it's more a case of most of the reps at the store simply plugging test results into their computer system and then going over the printout with you. There are a few there who do seem to have a pretty good grasp of what's going on. Again, how was I to know? It's still all pretty confusing. I can see how changing certain parameters in the CSI calculator affects the SI, but I'm still not putting it all together. Oh well, I'll get there I suppose. Agreed...no P in the Pool. :)
 
I would encourage you to review results from a few searches on effects of dry acid and adding sulfates to your pool. Not only is the dry acid more expensive, it does add sulfates which can damage grout, concrete and SWG plates. I'm no expert but the limited reading I did convinced me I didn't want it in my pool. MA is easy enough to handle and really isn't dangerous if you pay attention and use it carefully.
 
Hi,

Thanks for this reply. I have never heard of this issue with sulfates before, but now that you mentioned it I looked it up and do find some concerns about it. Oh well, I've been using the same dry acid product since 1989 and my plaster lasted 25 years. I don't use a salt water system so there are no plates to be worried about. I just feel more comfortable with dry acid, and find that it is recommended quite often over MA. Hopefully once the new plaster cures, I won't need to be making too many lowering-pH adjustments.
 
I didn't see anyone comment on this, so I thought I would chime in late to this thread...

A CSI of -.26 is greater than your -.30 etching threshold. With negative numbers, the closer you get to 0, the greater the value. So a CSI of -0.26 is less of a concern than a CSI of -0.34
 
It's a logarithmic scale of the product of calcium and carbonate concentrations relative to their saturation amount in water. A -0.3 means that the product of concentrations is roughly half the saturation amount. So either the calcium is half, the carbonate is half, or each is around 71%, or other combinations. It means the rate of calcium carbonate leaving the plaster is double that of it reforming. However, the rate of plaster degradation is mostly going to be a function of other factors where low pH is the worst. Also, well-made plaster is more resistant to the lower saturation index where issues in tank tests by onBalance weren't generally seen until the -0.7 to -1.0 range. For poor-quality plaster, however, issues can be seen with less aggressive water so anything negative could be an issue, especially below -0.3
 
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