1. I have a Sand filter....should it be on "filter" or on "bypass" while shocking? I've had it on filter, and I backwash it every day (the PSI goes up by 10) and nasty green is coming out...but is it better to kill the stuff first, then filter, or to filter 24/7?
2. What FC level can one swim in a pool at? I'm guessing one should be swimming in a pool at an FC of 15, but I wanted to ask.