I have a pentair clean & Clear plus 420 (4 vertical cartridge) system and was wondering...the instruction manual says add .75 lb of DE into the skimmer for each 100 sq feet of cartridge surface, it will improve the filtration. I had been planning on adding 3 lbs of DE to the skimmer.
I just added new filters in NOV.
I went to the pool store and a fairly knowledgeable pool guy said not to do that, it would plug the filter...
What say you all?!