CSI Following Stain Treatment


Silver Supporter
Jul 5, 2017
Dubbo Australia
Having just successfully completed a metal stain removal treatment I am very mindful that I must continue to add a maintenance dose of sequester, keep my pH on the low side (not to go above 7.2 for the next fortnight and would like advice on whether to keep it there for good) and that I should maintain FC as per the Chlorine/CYA Chart (CYA 70/FC 5) so as to prevent re-occurrence of staining.

Keeping my levels at the Acceptable Minimum as per your Recommended Levels (Fibreglass with SWG) when I input my numbers into the original Pool Math my CSI is out of range. It improves as I adjust the water temperature but is always outside the range on the negative side. Here are the levels I am aiming at:

FC 5

pH 7.2

TA 50 (to keep pH on low end)

CH 300 (hesitate to go any higher due to possibility of causing scale on salt water cell)

CYA 70

Salt 4300

Pool Temperature: CSI:

19°C -0.97 (current temp)

21°C -0.94 (range of summer temps follow)

24°C -0.89

27°C -0.84

30°C -0.80

Will this cause an issue over the long term?


Gold Supporter
TFP Guide
Jul 21, 2013
Northern NJ
Pool Size
Salt Water Generator
SWG Type
Pentair Intellichlor IC-60
CSI out of the recommended range takes months to cause damage.

Your signature says you have a fiberglass pool. With a FG pool low CSI is not a factor and it does not damage FG.
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