The return assembly going into my reef enters at the right end of the tank, but touches nothing that would allow the clean up crew to get to the plumbing. I designed that portion to be removable so that section's occasional soaking would be relatively easy. However, a couple of weeks ago I decided to park a snail on one return and let it get a meal. Within two weeks, that return is nearly completely clean, while the other shows a striking difference. I'm thinking about putting a second snail ...