CSI in an Above Ground Pool


Gold Supporter
Jul 17, 2016
I know that Pool School says that CSI is not that important in an UGP. However is there some particular CSI I should shoot for? In other words I have had CSI range from -0.22 to -0.97. Is this bad? When it gets around -0.97 should I add Calcium to raise it above -0.6 or just don't worry about the CSI at all?

Just trying to get the perfect balance in my pool. ;)


TFP Expert
LifeTime Supporter
Jan 6, 2010
San Dimas, CA (LA County)
There is no plaster to etch, so CSI doesn't really apply to you. What you need to watch is pH. Keep it between 7.2 and 7.8 for eye comfort and it will coincidently also not attack any metal in the pump or filter.