This is the first time I've owned a pool and I am trying to get a handle on all of the info here. If I plug in the recommended numbers for a fiberglass pool into the pool calculator, I get a pretty negative CSI number. After reading more on the forums, I see now that the low water temp will affect the CSI. I see now that I should let the pH rise a little higher to achieve balance.
I understand how important this measurement can be for plaster, but how will it affect fiberglass in the negative end of the scale?
I do have waterline tile and brick coping, so I am thinking I need to pay attention to the CSI for that reason as well.
I have been told by other sources that as long as I maintain a pH between 7.2 and 7.8, and keep the calcium between 150 and 250, the pool shell will be fine.
I am enjoying learning the info on this site, but until I become more educated, I want to make sure that I don't do anything that will cause damage to my new pool shell or my expensive heat pump.
My current test readings are:
FC = 0 (SWG is automatically off due to water temp)
Temp = 53 deg
CYA = 35
CH = 210
TA = 120
Salt = 2700 (I havent kept up with this while it's been cold. If the SWG is off I figure why fool with it.)
pH = 7.6 (I've been keeping the ph lower than I guess I should. I didn't know I should let it run higher during colder months)
This gives me a CSI of -0.36. So is this ok for my setup?
By the way, thanks to everyone for all the great info here.