I ordered a 100 lbs of BRS pukani dry rock for my 70 gallon. Got 12 one foot pieces and 3 two foot pieces. They are really huge and super light b/c they are so porous. I have 4 huge pieces left so I only used about 3/4. Wasn't too hard to aquascape and I love the look, wouldn't buy anything else. It's a little more expensive than other base rocks, but definitely worth it. You can ask for smaller pieces to create more caves and arches b/c you have a smaller tank.
“Success is walking from failure to failure with no loss of enthusiasm.”
- Winston Churchill