the more surface to the water, the more biological activity. That is why some people preferred the cylinder in the water (such as the old Tetra-billi sp? or many home made units) to the Jungle (and several other) Dirt magnets which sat on the bottom of the tank. Mostly the water just circulated through the top and sides of the dirt magnets (but not entirely because I've found a bunch of fertile eggs under dirt magnets). Some aquarists also complain about fish getting caught under dirt magnets and dying. I personally wonder if the fish died and was pulled under or was hurting, hid there and died. That type of filter can be suspended (short airline it) so all sides are to the water.
More recently there have been these modular sponge filters, Hydro Sponges, such as Ken's sells. Those get a lot of bang for a few more bucks and probably are yet more efficient. And a powerhead can be attached to some of them.
There are also power head/ sponge filter combos. For many guppy tanks they are too powerful in terms of current. I did take a pond sponge and put it on a power head in a 55 gallon tank. ;) It sure strained things out (mechanically). But I should pull it and clean it out more than I do when it is used.
NGB, which of those was advertized on aquabid?.
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