I have an ECCO (forget which, but it's the largest) that I used to use on a 20 gallon planted. I ended up using another small internal filter to add some water movement. I bought the eheim spraybar attachment for the canister, and eventually had to buy the Surface Extractor also, because there wasn't much surface disturbance and it would accumulate a whitish film (proteins and such). After spending all that money, I should have bought a Eheim Pro or a cheaper XP1 or XP2. I now own an XP3 for my larger tank, and I'm pretty impressed with the options, attachments, and quality of it.