In several of my past tanks, I've used the Emperor. I loved them. Now I have a current tank with AquaClear 30 and I love it too. I especially love how the carbon is on its own (replaced monthly). I just bought a 100 gallon complete tank and it came with two (2) Emperor 400. Now, I plan to have about half of the tank planted with EcoComplete and the rest with regular gravel with stack of rocks and open space. I am wanting to know if I should sell these filters and buy two AquaClear 70? I love having biowheels, but some people on here believe the biowheels will agitate the surface for faster Co2 escape. Edit... Actually, after a search on Google, it appears that the highest is the 110. I thought the 70 was the highest, since that is as high as PetSmart sells.