I always suggest the fluval/aquaclear 110 (also known as aquaclear 500). Its the only hang on back filter worth buying if you have a large tank imo and i know a lot of the keepers here would agree.
Shop great deals on fish tank filters at PetSmart. Keep your aquarium water clean and clear with one of our canister filters, power filters & more.
www.petsmart.com
The marineland penguins are ok but they are nowhere near the ac110 in terms of flow, media capacity, and overall quality. At any rate the smaller penguins like the 250-300 are not useful for your tank imo.