well, obviously mixing up and washing the gravel will get rid of some of the bacteria. they are not super glued to surfaces. however the bacteria in the gravel wouldn't matter *as much* if you have a filter like you have. (of course, as long as its big enough for your tank!).
ive got a tank which really has one supply of bacteria, and thats the filter. i have no gravel and the plants are kept inside small pots (the plastic ones younger or smaller plants are usualy sold in).
__________________
Give us a visit 
|