Well with getting a 4th FireMouth I won't be getting the Salvini's, so that helps a bit. Right now I'm doing a DYI Undergravel Filter for the 55g made from a plastic table from walmart, they come with 3/4" tubing for legs, so i can use the tubing for the uplift tubes on it, and im installing the carbon releases into the tubes, and covering the uplift tubes with rubber cufflings from home depot to seal the tops of them above the carbon. For the undergravel bed im using the table tops made from plastic with holes drilled into it, and the gravel bed over the table top. I think it should be good for an undergravel filter.