I would like to change out my original Topfin HOB filters with one with a biowheel. Can anyone tell me the difference between the Emperor and the Penguin (besides the spraybar)? Dr Foster & Smith have them on sale so now would be a nice time to make my decision. The difference in price is around $20 each and since I would want to change three tanks, is it worth getting the "better" one??? I asked the LFS but they didn't know the difference. Has anyone out there has/had both to compare?