Aquaclears are the best hobs. If you need one that says on the box "rated for tanks up to 50gallons" then the AC50 says that. But i would go with the AC70 or AC110. I have an AC70 on a 25gal tank. I only have the one sponge it comes with on the bottom in it and then the rest is biomax. works great.
Thanks guys. What about the emps. and penguins? The tank is a 40 gallon which houses my ruby greens and peacocks. I currently have an emp. 400 on it and want to add a new filter on.
I converted all my bio-wheels to ACs. The reason, cartridges. They are fairly quiet, you can pack the like you want them, and no buying cartridges unless you need something special right then. It's almost like a hang on the back canister filter.