The more live rock the better.
I had about 50lbs in a 20 H and I never had any problems.
I just set up my 71 and it already has 150lbs in the main and 25lbs in the sump.
when the tank is ready all the contents of the 20 are going over into the 72 so that will be another 50lbs making it 225 total. And I'll fill the sump with LR
until no more will fit.
, Live rock gives you a healthy System. Your rock will make you or break you.
If you don't want to pony up the cash for LR
for the sump just get some base rock and put it down there, it will turn into live rock in a months time. Remember, all the little critters that live in the rock are just a added bonus, what you really want is the bacteria and that stuff reproduces like MAD until it can't sustain itself and then it will stay at a healthy level.......sooooooooooo the more LR
or base rock the better.
Do you have to increase the amount of LR
though? Nah you are okay.