With ALL fw tanks, if it is well planted, you don't 'have' to do gravel vacs. I know you don't have to gravel vac around the plant roots, since the dirt will be taken up by the plants..... I just generalise it and leave all the 'dirt' in there (I do my weekly water changes). As long as you don't have fish that stir up the gravel too much, you can see a layer of mucus forming underneath the substrate (you can see that from the side). I don't know if it's generally recommendable to let this happen, but it's just my way of doing it, and I have never encountered any problems whatsoever.
Which brings me to the snails. These Malaysian trumpet snails help by crawling through your substrate, bringing all finer dirt particles between your gravel and eventually about a cm below the surface.
One of these snails hitchhiked on a plant, and now I have literally several hundred in both my tanks, of all sizes. Largest snail I have is about an inch long. They live on remains of food and plants. The reason my population is this big, I think, is because the algae wafers I give crumble allot and half of it sorta dillutes in the water.
If you want to see the 'mucus' check out my thread in
FW tank show off, 18.5 and 28.5
gal. In the updated pic of the 18.5
gal it is clearly visible.