In a given volume of sand, the usab

In a given volume of sand, the usable bacterial surface area rises rapidly as the averageparticle size decreases. For example, a cubical particle 1 mm on a side has 6 square mmof surface area, while the surface area on a particle that is one eighth (or 0.125) mm ona side is a total of 0.09375 square mm. However, in the volume of 1 cubic mm, therewould be 512 of the smaller particles, for a total area of 48 square mm, eight times whatis found on the larger cube.The total sediment surface area in even a small tank is impressive, indeed. In my 45gallon reef tank, the sand bed averages about 4 inches deep, by 12 inches wide, by 36inches long, for a total of one cubic ft of sediment. I won't bore you with thecalculations, but if the average particle size is one eighth mm, and that is a goodaverage size to have, the total sand surface area is about 14,828 square feet or justslightly over 1/3 of an acre. A LOT of bacteria can live with that amount of space!