in my more intricate tanks, like this one http://www.frogforum.net/vivarium-te...aludarium.html, i like to build in a "maintenance tunnel", so i can access any equipment, in case of failure. it also gives me a place to run a siphon tube so i can change 50% of the water on a weekly basis.

for vivs that i build using a drainage layer that isn't a false bottom, like this one, http://www.frogforum.net/vivarium-te...ach-coach.html i place a piece of sponge at the bottom, cut a slit in it, insert aquarium air line into it ans run it out the top so i can siphon off extra water.

as far as cleaning the substrate and what not, microfauna (springtails and isopods) are invaluable.