Every once in a while I search for some evidence to support the whole "high-tech filters are better than a sponge filter" theory but I have yet to ever find any.
I think the debate between effectiveness of high-tech filters and sponge filters is a different conversation than the effectiveness of high-tech filters vs. substrate. There is a lot of evidence to show that modern high-tech filters provide more surface area for bacteria colonization than the average sponge filter, however sponge filters not only provide a surface for bacteria growth for biological filtration, but they also provide direct mechanical filtration as well. Therefore a comparison of effectiveness between the two would be pretty difficult to accomplish.
Some references for you to look at;
That last one is an advertisement, but contains information on the actual surface area of bacteria and sand grains.
You have to have a decent plant mass for this to work.
To have no water movement at all, would have to be determined by the inhabitants and types of plants. some fish need water movement to be happy. Some plants grow too slow to do well without water movement to remove sediment and discourage algae growth. A good cleanup crew would be essential too (shrimp and a moderately small snail population). People mention water movement for nutrient dispersal, but I think an active fish population can help provide that. Nutrients aren't being depleted that rapidly in lowtech tanks.
I wouldn't recommend this though for tanks that don't get observed frequently. Just setting it up and leaving it to its own devices could be disastorous for the inhabitants.
I think another factor you would need to consider is substrate. If for example you are using a very fine sand with no to minimal water movement, then debris is quickly going to settle and fill in the void space and surface area of the sand, reducing your effective aerobic zone for bacteria colonization to only the top surface area of your substrate.
NavyBlue, FYI fish don't actually put out waste from their gills (other than CO2). Gills are strictly for breathing. Look up the osmotic process, which is where GH and KH come into play for proper hydration and expultion of waste for freshwater fish (for salt water too, but salt water fish actually drink water constantly and also use the process to regulate internal salt content)
Actually, not quite.
Just a brief introduction. A quick google search will quickly reveal lots of scientific abstracts on the subject if you want to look into it further.