Originally Posted by
geo57
Sand is a better substrate than gravel because feces and food are less likely to become trapped. However the sand at the top still collects a biomass because food suspended in the water column will stick to the sand particles at the top and thus collect to form a biomass.
If food collects on the sand and causes a bio-load as you say, i would assume it will also happen on glass at the bottom of your tank. I know this is an old thread but i just have to say a bit of this logic is failed and faulty. Also when i clean my sand i usually vacuum up a bit of sand, leaving my bottom cleaner than a bare bottom tank. Unless your speaking facts it's all speculative, logic can be bent in many ways my friend.