if you have a heavily planted tank, what would happen if you didnt vacuum the substrate but just performed regular water changes? would the bacteria break down all of the bi-products of the waste? dont the plants use the waste too? i have four adult angels, 4 red eye tetras, three clown loaches and two cory cats in a 29g. oh i also have a buch of malayan needle-point snails that burrow into the substrate(2 inches of gravel with one inch of sand on top.