I have a combination of HOB, sponge, and 2 canisters – FX6. I have 3 size of the Marineland “emperor” series – sorry can’t remember all three names. Catch these on sale and you can’t beat them. They are my go to for 20 gal plus tanks. I have a sponge filters on most intakes and stand alone filters as a secondary filter in most tanks. The canisters are on my 2 big thanks. Sponge filters are my least favorite – I just don’t like squeezing them out.