I searched the forum and couldn't find an answer to this question, and I sent an email to Hydor a week ago with no response, so here's hoping someone might be able to help. Hopefully it's not a completely stupid question. I don't have enough room to hang the Hydor ETH behind the aquarium, and I really don't want it to be visible hanging to the side. That leaves placing it inside the cabinet as my only option. I'm sure most of the people reading this will wonder why that's a problem! There's no real problem. It's just that positioning the heater on a Eheim 2028 or 2217 outlet involves a lot of twisting the tubes down and around to make things fit, and that slows down the flow rate more than I'd like it to. Plus it makes the cabinet messier than it needs to be. The inlet of a 2217 is at the bottom of the canister, and that means the heater could be positioned directly above the inlet barb. No annoying bends in the tube, no excess loops of tube, problem solved. Obviously the heater might need to be cleaned more often, but does anyone foresee any problems with this setup? Hydor recommend placing the ETH on the outlet, but I don't know if this is simply for maintenance reasons, or if there's some other technical reason. Thanks for any help.