No need for both UGF and canister. The UGF won't really suck in and hide all the uneaten food, it will kinda collect near the surface and decay, the decayed stuff kinda collects under your UGF. Your mid and top feeders will feed off the bottom if there is uneaten food there, but bottom feeders are way more efficient at it. Since you can get all the filtration you need in a HOB or a canister, I see no reason to use an UGF since they can collect some serious amounts of muck under them, and they are impossible to clean without seriously disturbing the tank. But they do make your substrate more efficient surface area for bacteria due to the water flow through the substrate, and they do work.