yote
In Memoriam
Of course you can use base rock,which is quiet a bit cheaper to bulid rockwork with.Then seed it with a few pounds of the live stuff.
Piggy is right on -- 1 to 2 lbs per gallon. So for your tank, 80 to 160 lbs total. She is also right in saying that if you use all live rock, your cycle will be quicker, and your tank will be ready for fish faster. If you use a lot of base rock, it will take time for the bacteria to colonize the base rock.
I learned from a pro.