I have a sponge filter in my 20g tank and 10g betta tank. But they are only for back up. They work really good at helping with biological filtration and save your but if your main filter goes down. But sponge filters are primarily for breeder tanks where a large filter may suck up fry.
If you are using that filter on any thing smaller then a 10 gallon tank you really need to have a baffle on it. I use the same model on my 10 gallon and ya it really moved the water before I placed a baffle on it. Here is a link to a post by Kim
on how to make a baffle! http://www.bettafish.com/showthread.php?t=30139
. I use this on both my tanks and it is super easy to do! Hope this helps