Understanding CSI?

[DrC]

I am enjoying the new pool with my switch to SWG. I have not had to make any adjustments to the pool in the last 5 days since starting my SWG a week ago. My only regret is I did not make the switch years ago. Now looking at my PoolMath Numbers daily I have questions about the CSI level. First off, does it matter with a vinyl lined, steel wall, above ground resin pool? Here are my numbers for the last 5 days with the only change being the water temperature that is averaging 90 degrees with my Solar heating. I test every morning at 7:30.

FC 6.5
CYA 70
CC 0
PH 7.5
TA 80
CH 100
Salt 3200

PoolMath calculates the CSI at -0.73 and states that "Greater than 0.6 is suggestive of problems for all pools." Changing the numbers in PoolMath it appears that changing the CH is the easiest way to adjust the CSI. If I adjust CH to a 130 level PoolMath calculates the CSI as -0.61. My water is sparkling and crystal clear. I am hesitating to make any changes that I am not sure I need too.

Thank You
Dennis

 

[smackdab]

You nailed it. It is because your CH is so low. CH is a big factor of the CSI calculation I think and pH is the other one. Since you have a vinyl liner I wouldn't worry about it. If you had a plaster pool, the low CH could start to eat the calcium out of the plaster.

 

[chiefwej]

A number of factors influence the CSI, (including pH, TA, water temperature, and CH). While CH tells you how much calcium is in the water, the CSI (Calcite Saturation Index) tells you if that calcium will perciptate on the surface of the pool (as scale), or damage plaster and concrete, by drawing the calcium out of them. If you have a vinyl lined pool you need not worry about a negative CSI below -0.6, but a positive CSI above +0.6, will still cause scale.

 

[Richard320]

You have a vinyl-lined pool. You don't need to worry about low CSI because there's no plaster to damage. High CH can lead to scale formation, that is true no matter what surface. In your case, you are way, way, way below +0.6 CSI, so you're not at risk, so don't even worry about CSI. Don't waste time, money, or worry on it.

 

[DrC]

Thanks for the replies. I needed the confirmation of what I was thinking but wasn't sure. Test were still good this morning. FC was down a little but I think that might be the 100+ water temp, LOL. The solar controller dial got bumped and I hadn't noticed it.