Hello folks- I've had a 29 gallon tank going with a Marineland Penguin 200 (rated for 30 to 50 gallons) for just over a year. I really like the filter, so was planning to go with the larger version (Penguin 350, rated for 50-75 gallons) for the 55 gallon I am just now setting up. But the thought occurred to me that it might actually be more efficient to use multiple filters for the 55 gallon, possibly two 200's on each end. Or possibly the 350 with a 200 on the other end. I just don't see how having any filter on one end of such a long tank would be practical or effective. What are your thoughts? Has anyone done this? Before you suggest it, for a variety of reasons I am not planning to use a canister filter at this time. I use the customizable inserts in the HOB filters, so I can get real creative with my media. Plus I like the aeration the HOB's provide, and even the sound.