First year with pool trouble. I have an AGP 24' round. New 1.5hp pentair pump and 250# sand filter new at start of season. We have had our pool for 12 years with only minor problems. This year our cover tore over the winter and allowed debris into our pool. Upon setup I had a major malfunction with filter. It looked like a water fountain. So I purchased a new pump and filter which took me a few days. We stated developing black algae on bottom of pool. (at least that's what I think.) I initially shocked with 4# of shock which helped some. The past 2 days I shocked with 6# of shock for 2 consecutive days. After the first day i noticed a significant difference. After the second day still have spots on the bottom. I have been scrubbing, vacuuming daily and filtering constantly. I know patients is key. Just want to make sure I am on the right tract.