Inbuilt Filter/sump?

[Rorie]

I just picked up two new 3 foot tanks. At one end, there is a 6 inch tall 'divide' from the base. The guy said they are ex-pet show tanks. He gave me a pipe which sits in this divided section. He said to fill it with substrate, and attach at airline tube to the pipe. This would then act as my filter by pulling the water through the substrate, up though the pipe, which then has a 90 degree bend where the air will come out.

So how good is gravel as substrate? Would i be better filling it with sponge? Or bio balls?

And how, when forcing air down the tube, does it suck up water?!

 

[england]

Gravel is good at holding bacteria, yes so is sponge and other materials..
Remember before the days of great filerations we had to make do with undergravel filters..

 

[Rorie]

Thanks for the reply.

So, now that we have moved on from under gravel filters, and because i am wanting to use this tank as a grow on tank for my fry, is it best to use filter media of various types in this section, or just use my air driven sponge filter? Or both or what?