I defer to your professional expertise, and I will heed your advice regarding my 24-year-old sand filter. I recently had an extensive whitefly infestation, and I surmise that the honeydew film and insect eggs that ended up in my pool have caused my current persistent cloudy water condition. I'm SLAMing, brushing and flushing my sand filter daily. My water chemistry is TFP spec.. . . many of us have NEVER changed our sand and have no intention to do so . . . a properly operating sand filter can (and usually does) leave your pool crystal clear. Sand is a perfectly acceptable filter medium which sort of explains why it has been around so long . . . the solution is frequently found in proper water chemistry or, less likely, some type of mechanical damage to the filter. Less often, the pump and filter are simply not being operated long enough to keep the water clear . . .
I'm considering using CV-600 Catalytic Enzyme Water Cleaner to restore/enhance my water clarity.