I've read several places about using Fiber Clear (DE alternative) in cartridge filters to reduce the micron rating and 'polish' the water, so thought I'd try it out this year. I bought a 9 oz. bag and started dosing the skimmer a little at a time, and kept checking the pressure for the 1 psi rise, but it never rose (verified working pressure gauge). After dumping nearly the whole bag in and getting no pressure rise, I finally looked at the pool water and noticed it was getting cloudy. Whoops. So since my cartridges were 5 years old now, I bought some new ones and started over. Once again I fed a whole 9 oz. bag in (this time the water stayed clear), still no detectable pressure change. Since my filter is 420 sq. ft. (my research here and other places tells me that's way overkill for my 10,000 gal. pool, but I'm not changing it), I'm thinking it might take a lot of Fiber Clear to bring the pressure up. Would you agree?