A pleco/guppy breeder gave a talk at my local club recently, and one of the filtration methods he employs is basically a deep sand bed inside a pitcher.
So he takes a pitcher (in his case an empty Brita pitcher)
puts a hollow tube in it with an airline
fills the rest with substrate
puts this in his sumps (I think, or maybe in his tanks)
and turns on the air, which creates water movement down through the deep layer of substrate (he makes sure it's at least 6 inches to create the anaerobic effect) and up through the tube.
Anyone see any problems with this method of filtration? There is no need for creatures to sift the top layers of the bed as the water is flowing through it due to the airline. But would it cause problems with the anaerobic bacteria at the bottom because there is so much water moving through it (instead of the gentle, slow movement a DSB usually has)?