normally i do not go by weight content but by volume...as in how many inches of sutrate ... Id say somewhere around 4"+ of subrate should be suffiecient ... I like to keep more than other tanks if dealing with cichlids though as you know what there habbits can be like
Sorry, should've added that. Thanks Snow. I was assuming around 2"-4" of gravel. I have anywhere from 2-3" in my tank. You can quite easily calculate the volume. Just decide how deep you want it to be and multiply the LxWxH (L&W being the footprint of your tank) and there's your volume in cubic inches. Then you just have to conver that to whatever it is they use, cm cubed is it? I can't remember. I didn't buy mine in bags as it's expensive, it was done by weight which is why I neglected volume. I paid $2 for my 100lbs of gravel.