I ordered 4 sheets of 1mx1m x3cm thick sponge. I got 2 grades of sponge, Course 10ppi and Medium 20ppi. I also got 20 of these up-lift air-driven pumps.
Up-lift tube and coarse sponge
Medium pore sponge
I measured up a 30cm x 34cm piece of sponge. I cut it out with a box cutter.
I cut a length of PVC
pipe to fit across the side panel of the aquarium (29.5 cm) Then I put it in the aquarium on the glass. I put the sponge in, resting against the PVC
pipe but not against the heater. Then I put in the gravel to hold the sponge in place. I put in used gravel from my aquarium without cleaning it so I can see the Mattenfilter work. (I turned down the flow on the existing sponge filter.
I cut the top piece of the uplift tube in half. It needed to reach just beyond the edge of the sponge. I cut a notch in the top of the sponge for the outlet of the uplift tube. Then the airline was connected to the uplift tube and a suction cup and clip used to hold the uplift tube in place.
I am hoping this design helps de-clutter the fry tanks, no heaters or round sponge filters to bump into when catching fish.