Erik wrote: << One last question, how do you deal with the mechanical filtration with < this setup? It sounds like you would skim any surface muck down into the < undergravel, and you'll just settle all your waste just on top of the < gravel, right? >> Not quite. The whole point of reverse flow is to get the stuff below the gravel. Everything colid settles on the bottom of the tank, below the filter plate. As far as I can tell, the fatty and proteinous stuff that skims off the surface floats back up through the gravel, and is consumed by plant roots, and bacteria in the gravel bed. Most people say you shouldn't put things like rocks or whatnot onto the surface of the substrate because it will create dead spots. [ But if you don't overstock, the dead spots should turn anaerobic. As far as I can tell, the stuff off the surface, which some people remove in salt-water setups by foam fractionation ( protein skimmers) , is the same stuff they reintroduce later into their anaerobic filter chambers as "bacteria food". ] The couple sentences I have placed between brackets is purely personal conjecture based on what I can glean from magazines and personal experience. If I'm right, this should help keep the nitrate levels down between weekly water changes. What I know for sure is that when I changed intake guards from the fan style to the straight to improvesurface skimming, the surface cleared up in a couple days. And yes, sure , you can include this stuff in your article. I'm going to check out the web page you refered to tomorrow. I'll let you know how it looks.