Sponge filter?

[iMax]

It was suggested I use a sponge filter for my 20g planted, I don't have any knowledge in them or how they work, would one suited for a 40 gallon tank be suitable for a 20? Would I need to add power heads or air stones to make up for what a hob normally does?

Any info would be helpful

 

[iMax]

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[azmodan]

I think it was recommended because you said you're gonna have RCS. You can always just run a regular HOB filter and put a prefilter sponge over the intake tube. The sponge part is important because baby shrimp can often get sucked up into the filter if there isn't a sponge covering the intake tube openings.

The prefilter sponges can be found easily online or at your local LFS for a few dollars.