I have heard wonderful things about sponge filters and I am thinking of switching my tanks over to them. However, I wanted to find out some more about them before making a purchase.
First off, how strong is the water flow? With my betta and floating dwarf water lettuce I don't want anything that pushes around a lot of water. Also, kind of related to this, is the filter compatible with sand substrate? I wouldn't want a bunch of sand sucked into it.
Lastly, other than the sponge filter itself is there any other additional equipment I would need to purchase. I am looking into getting the Hydro 3 sponge filter and noticed that many people also buy air pumps with it. Is this a must or is it just for increasing water flow through the filter?
Any advice is greatly appreciated.