I use these  in all my betta
tanks (about 53 at last count).
This one is for up to ten
gallons. These work well in
spawn tanks and grow out
tanks for fry.
my Favorite Things for my Bettas
This filter is so easy to hook up and make
soft, clean water for your aquarium. Comes
with great instructions. My fish love their
new water.
Blue Marble HMPK