Also Urbor, I believe that it depends on where you plan to keep the LR...I mean, if you will have a fish room or a big sump to place some LR then yes by all means get 500 lbs but if all your LR will be going in your display tank then you have to decide what type of aquascape you plan to have. YOu can go with open swimming space and the "less is more" type of rockwork to give your fish plenty of swimming space and corals room to grow or you can add lots of well positioned LR to offer plenty of hiding spots for your fish and lots of real estate for corals to be placed. Decisions, decisions huh? Good luck with whatever you decide to do.