OK guys when you use your gravel vac.

[darburks]

do you push the gravel around to get the brown gunk or do you need to leave it alone?

[sir_dudeguy]

well, it depends...if there is lots of junk in there, and its coming up out of the gravel, and not just on top, yeah, but if its just on top, i dont, because theres bacteria in the gravel/sand i believe. Also, if you get sand, then you dont really have to worry about stuff getting under it like you do w/gravel or pebbles or whatever you wanna call them

[QTOFFER]

All that brown gunk is decaying food, plant matter, and fish poop. After a while, it breaks down into very fine particles called mulm - basically fish manure - plants send out roots in search of it.

I try to remove as much as I can without disturbing the roots of my live plants. Once a month, I lift the driftwood and stonework and vac out the gunk that collects beneath.

[TomK2]

I deeply dig the vac into the gravel to get as deep as possible, but I do not swirl the gravel. I try to get as deep as I can, without stirring it up too much.