CSI and best way to adjust it

[Hobbsks]

FC 3
CC 0
PH 7.2
TA 80
CH 180
CYA 30
CSI -0.71
My thinking is the CSI should be as close to 0.00 as possible... am I correct in this thinking?
What is the best method to raise the CSI without throwing everything else out of whack?
I have been using the PoolMath App and thanks to the great wealth of information on this site the pool has been in the best shape with the least amount of work. So a GREAT big thank you to everybody here!

 

[Oly]

I have not run your numbers but I'm guessing let your pH drift up to 7.6 - 7.8.
Plug your numbers into the PM app and check it out.

 

[Hobbsks]

I have a little but I didn’t know if raising the TA or PH or both was the best idea. I will mess around with the Ph a bit more and see what the app says

 

[Texas Splash]

CSI is influenced very quickly by pH and water temp. But remember that CSI is something that is a concern primarily for pools with concrete/plaster materials and/or pools with SWGs in areas that have extremely hard water (potential for scale). I don't get that impression from your pool, equipment, or location, so CSI shouldn't be something to worry about. Simply stay within the TFP recommended ranges and you should do just fine. Enjoy!

 

[JoyfulNoise]

You have a vinyl liner pool so CSI being low is not really critical. If you have a heater or SWG, I would suggest keeping your CSI closer to zero but that should be easily achieved by raising your pH to 7.6-7.8 range and not letting it go lower than that. If your pH stats consistently low or gas a tendency to fall over time, I’d suggest raising your TA to a higher value, about 100ppm or so.

 

[Hobbsks]

Thanks for the tip about the heater! You reminded me I needed to add that to my signature!

 

[JoyfulNoise]

Thanks for the tip about the heater! You reminded me I needed to add that to my signature!

Metal corrosion inside a heater core is influenced mainly by pH. Monitoring CSI is a good “proxy” for warning a pool owner that metal corrosion is possible but it’s not an index that was meant to be used for that purpose. CSI is strictly related to the solubility of calcium carbonate in pool water. The are other corrosion indices that would be better for metal corrosion but they are generally not applied to pools as the industry prefers to use the general Langlier Saturation Index (LSI).

So, in your specific case, I wouldn’t worry too much about CSI but you’d be better off keeping your pH higher and your TA up if your water tends to drift down in pH.