Can anyone provide the formula for CSI? I'm not looking for anything ultra-technical. I just wonder if there is a CSI formula (even a simplified version) that is similar to the LSI formula Si = pH + Ti + Ci + Ai - 12.1. Ti, Ci, and Ai come from the LSI supporting tables. I know that CSI is more detailed and brings CYA and salt into the equation, possibly along with other things. I know that TFP prefers the CSI over the LSI presumably b/c it's more accurate and is based more on the total chemistry of your pool. I have incorporated the LSI calculation into my pool test log spreadsheet, and I'd like to do the same with the CSI if possible.

Here's an excerpt from my pool log. I enter the test results from a test session, and the LSI is automatically calculated. But, I'd prefer to use the CSI if possible.

Date FC TC pH Ca TA CYA Tmp LSI Notes

4/25 7.0 7.0 7.7 180 90 55 71 0.00

Thanks.