I need two canister filters for my 180 gallon, since it is drilled with two overflows, and I need a canister for each overflow. I have been leaning towards getting two Eheim 2217s, but I'm a bit worried they won't be powerful enough. Each canister is rated to 159 gallons, but I heard that two still might not be powerful enough for a 180. I'm just planning on having one Jardini Arowana in the tank. Thoughts?