| The absolute very best for water polishing is an upflow sand and gravel filter with an air blower for cleaning. Fines filtering is about the density of the media and the rate at which you push water through it. A 55 gal drum sized filter shouldn't flow more than about 1800 gph if it's job is is water clarity. After that it's about a fine mesh and how easy is it to clean. The fine cut "bactitwist" at 3/32nds of an inch wide is my next favorite. Both of these out perform open floating media hands down. Try to keep a flow rate of approx 630 gph for each 1 sq ft of crossection surface area (either diameter in a round tank or side X side of pads or matting in a square tank). The faster water travels through any media the less the media will be able to trap. |