I have brought up low CSI a couple times in threads recently and been (gently!) corrected. I don't mind that, as an Advanced Beginner I kind of expect it from time to time. But it leaves me wondering what the story is. I guess I'm just sensitive to CSI as I have a plaster pool myself and have had balance problems. I don't want to add plaster patching to my list of grumpily attained skills.
Really I'm not sure how much of a problem a low CSI really is. If all your numbers are at the low end of commonly suggested ranges, especially with pH down toward 7.2, then your CSI could easily be in the neighborhood of -.6 and that's not so good. But is it not so good in a this-week sense, or a this-month sense? (Or a this-year sense??) If the former then I feel it ought to be mentioned, if the latter then yes in a green pool you clear the algae first and see where you are afterward.
There are a few Deep End threads about CSI that I found.
- this is a mind-numbing discussion of negative CSI but concentrates on metal corrosion not calcium leaching.
- this is basically a disagreement about what the don't-care limits are.
- this is by chem geek discussing aspects of CSI, and among other things he notes: "That would mean that for dissolving of pool plaster, pH is the most important factor. It is only for scaling where the TA and CH play a significant role."
But... how fast does all this happen? Days, weeks, months, years...