I lucked out today and picked up a 20G AGA Hex with wood trim and stand for $25 at a garage sale! It was day for fish, also saw a 30g with stand, filters, heater for $20. Anyway, I want to get a filter for this hex and like the Emperor but the slot in the hood is only 8.5" and my emperor (I have another 20g) is larger than that. Since the stand is enclosed with a door I was also wondering if I should get a canister (this will be in the dining room so I'd like a clean look). I have never used a canister filter and would like to hear some opinions about which HOB would fit and whether a canister would make sense. Stoicking will probably consist of 2 severum.