Perplexed and need help

I ordered 30 pounds of Pukani from BRS and they sent about 35. I have a JBJ Nano 28 LED Advanced. I'm new, and the guideline is 1 to 1.5 pounds per gallon. I'm perplexed because there is no way I can get that much rock into the aquarium unless I leave no room for water or corals! I have a nice scape with about 18 to 20 pounds of rock and I'll be adding about 5 more pounds of live rock from my LFS. I am guessing that the reason that all of it will not fit is because the Pukani is so light and porous. That being the case, will the porosity of the rock cause 18 pounds of it to create a sufficient bacteria colony for filtration?

Thanks in advance.

 

It's very porous stuff, 18lbs should be fine.

 

Thanks!

 

also 1.5 - 1 lbs. is real live rock! so you have to count water weight. water on the rocks will add so much weight.

also i never go by lbs. any more. all rock is different, its a guide line i would just put what looks the best, and if it is not significant rock more water changes or rock in the sump! hope that helps ;D