First of many thanks to this forum and how its been extremely helpful. 4 years ago I had a 15k gal fiberglass pool installed. Using the liquid bleach everyday and a little muriatic acid once in a while I never seem to have to add anything else. The only time I've ever shocked is each spring when opening.
My total alk always seems to stay at ~90 +/- 10
Ca hardness has gradually increase from about 140 to 190 in 4 years time
CYA has always between 30-40
my question is: Do I need to decant some of this pool water (say 50-75%) and make up w some fresh( municipal) water just because of of its age?
It just seems weird swimming in water that is 4yrs old ( only new water ever added was for evaporation and splash out) even though water current water appears fine.