[Aquarist_Fist]

I was only talking about a simple sponge filter setup driven by an airpump. If you are not planning to overstock your tank and if you only do RCS, this will be absolutely sufficient. I use a Hydro II sponge on a 5.5g and never had an HOB/powerhead. I also never bothered to cycle the tank. Good water, Prime (or a similar product), and of course plants do the trick. Shrimps have a tiny bioload.

In general, filtration for reasons of oxygenation is overrated. Solid stocking and a healthy plant grow are much more important than filtration. When I was a kid, my neighbor bred blue discus in a 75g tank without filtration.