I'd recommend the power filters from AquaClear......The most "bang for the buck".
Although I think the smallest size filter AquaClear makes is the AC20 which has a flow rate of 100 gph
. Maybe too much for a betta? Sorry no experience with Betta's. Maybe somebody else can chime in......with the proper size filter (gph
flow rate) for a Betta tank?
I've also had good luck with the Marineland Penguin filters.
GREAT idea using a sponge for a pre-filter!
Goodluck on your Betta tank venture!