I have 200lbs of rock in my 125g. Ifindit just the right amount and there is actually swimming room in back of the structure and plenty of caverns and overhangs. Your live rock is your primary source of filtration in a sw
tank so the more the merrier.
You can add 100lbs of base rock and 20lbs of live rock. the live rock will seed the base rock in a few weeks and in a couple months you won't be able to tell the difference between the two.
My 125g has only benn up a few months and it's full of coralline and I can't tell the base from the live. The only clue is the base rock is prettier, at least to me.
I think coralline has to be in the tank at some point for it to multiply so get soem live rock with some nice purple.