I needed one for my 180g so did some digging. Found that for less money I could by a Magnum 350 canister filter and get the best of both worlds. I have a large w/d that feeds a double stack 100um Inland Seas Nu Clear filter followed by Inland Seas Nu Clear BioBall resevour. Waaay overkill on the filtration but it sometimes misses the smaller stuff. Solution - I purchased the 350 (comes with both standard carbon/fiber filter and what they call a polishing filter) and a 10lb bag of swimming pool DE powder (for $10). Set it up as directed for polishing then add ~10 tablespoons of DE. Runs like that 24x7 and tank looks great. If I need to kick it up a notch, I double the DE dose and run it over night. By morning the filter is used up and the tank looks great. I did overdo the dose once and notice that the filter clogged quickly and started releasing DE into the water.
