New ten gallon getting set up for our betta. Decided on hydro ati sponge filter 2 since I saw several suggestions that more filtration and surface would be advantageous (that filter actually works for up to twenty gallons.). Our boy does not like current at all, so even the bit that comes bubbling out (tetra small whisper pump) could be bothersome. To calm that, I grabbed the fluval prefilter sponge from another tank and trimmed it to fit on the top of the outflow tube. This really seems to do the trick while still letting the filter run with a good airflow.
I haven't used sponge filters before, so I just wanted to double check with the knowledgable folks here to make sure I'm not negating the workings of the filter in some way. I'm having trouble linking to the photos here on my phone, but there's a couple of pics under my album "new tank."