Suggestions on skinny HOB

[StreetCypher]

I'm looking to add another filter on my 55g. Right now i'm running an XP2, and was looking to buy an AC500. But, it occurred to me that theres only ~4 inches behind my tank and the wall. The AC500 is a fat filter, so it won't fit. Any suggestions on a brand/type of HOB thats skinny?

[Seaman]

I would assume most that would fit, will probbably not be sufficient enough turnover rate, being that they will be smaller filters. I would suggest making a fluidized bed filter, for its size it will be the most biologically active filter. It should be pretty easy and cheap to make it out of actylic.

Here's what you can do, get some acrylic cut to make a shape like below, make sure the cuts are nice and smooth so it seals good, drill a hole for an inlet and outlet on the topthe inlet will come from a small pump in the tank (thats prefiltered) and the outlet will go back into the tank, just use PVC to make the inlet and output, make sure the inlet pipe goes almost all the way to the bottom, then before you put a pipe in the outlet hole, put about a 1/4 inch of pea sized gravel in it, then cover that will about 3-4 inches of sand (make sure you leave quite a bit of space above the sand so it doesnt get sucked out the outlet. then you can attach brackets so that it will hang on the back of your tank. Just make sure that the whole thing is sealed up pretty good, because it works on pressure, also make sure your pump isnt tooo powerful to blow the sand out in your tank.

Here's a diagram:
http://www.imagestation.com/picture/sraid142/p122ea2fa9496e50b94feff856108b719/f6a6e4b7.jpg

[StreetCypher]

Thanks Seaman, i'll look into something like that.

I was thinking that the only HOB that would fit would inadequate.
How about another canister? Waste of money?

[Seaman]

Fluidized bed filters are actually very good, they can handle high bioloads, and can adjust to changing bioloads very fast...so if it were me I'd make a DIY fluidized bed filter...and then use the canister filter with micron pads to polish the water