The weird thing is, when I had my 29 gallon tank a few years ago, i threw my gravel vac out because it was useless, and that tank was WAY overstocked, I just had a good cleanup crew i guess. I had 2 10" oscars, a 12" pleco, a 6" rock bass, and 4 blue paradise gouramis. My "cleanup crew" consisted of a 6" goldfish(a feeder that survived long enough to get big), a 3" corydora, and a dozen kuhli loaches. I kinda figured a hundred or so MTS would do as good a job.... guess not.