How much sand to get? How much rock?

[Briko03]

Is there a rule of thumb for how many lbs of sand I should get per square inch? I have a 24x24 cube and I was hoping to have enough sand for a DSB. Not really sure how to translate that to lbs. I also plan on ordering some dry rock, does the 1lb / gallon rule really apply even with the porous rock like key largo (from Marcorocks).

 

[143MPCo]

not really a "rule", but you'll need roughly 120 lbs of sand to achieve a 4" deep sandbed in a 24 x 24 inch tank.

 

[143MPCo]

that's assuming the sand weighs 90lbs a cubic foot.

 

[143MPCo]

Rock is a bit more subjective, you can go the 1lbs per gallon or not, but consider that it's one of tanks key biological filters (so to speak) that we have, and you might want to considering adding much more... now a days I hide as much as I can in my sump, if you don't want to do that you'll have to find other means of providing area for bacteria to grow and thrive.