I have one on my 30 gallon. I really like it too. It is 400 gph (duh) so it should be great for a 46. If you don't have a fuge, then you can use one of the compartments for cheato and just add a light. They are great for the price too. My lfs was trying to sell one for 75 dollars, but I got it at petsmart (which sucks for most things) for 42 dollars.