Ive really never fallen for that. I just aquascape the way I like. If I decide I want another rock I add it if not I take one out. Ive never had close to 1.5 lbs per gallon.
Don
I did once, then I sold about half of it to one of my friends. When I first started this 300, I had 300 lbs, and only used about 250, I ran out of room!!!!!