Hi! Thank you so much for your work here and the advice you've given the old crowd at Ben's forum! Since that forum is now all but defunct, I would like to ask a question that I haven't seen answered yet. When opening my pool this year, I had quite a bit of debris. In order to remove as much as I could as quickly as I could, I tried vacuuming to waste. I noticed that I am seeing the fine debris (sand, dead algae, etc.) coming from the returns while vacuuming to waste, which should not be happening. After changing the multiport valve back to filter (AFTER backwashing and adding more DE), I found DE coming from the returns. I feel like there may possibly be a tear in one of my grids, but I don't know that this would explain the dirt from the returns while in "waste" mode. Any words of wisdom?
It's kind of sounding like your multiport valve is the issue - the spider gasket perhaps. When vacuuming to waste there should be no debris going to the filter, everything goes straight to the lawn. Is your filter/valve very old? Since you've had it, have you been careful to turn the valve in one constant direction and not go back & forth (left & right)? Changing directions has been known to bind or crimp the rubber spider gasket at times.