Depends on what rock you use. I have less than 100lbs of Pukani in my 220 and not much room for more. But then, I like a minimalist scape too. You need to treat/cure any dead rock you get. No matter the source. In my case I bleached my pukani for a a couple of days, then soaked it in tap water for a couple of days, bathed it in muriatic acid for 15-30 minutes, and soaked in RODI for a couple of more days. Bleach, acid, and baking soda to neutralize the acid cost me maybe $20 while the process cost me a week of my time. It's the way I did it but not the only way. Other's have had great success simply curing it in a rubbermaid and a few weeks to months and water changes to draw out any phosphate.
Do not fool yourself into believing you can take short cuts in this hobby and that includes tossing rock straight in and hoping for the best. No matter the source, treat it like it's full of phosphate until you know otherwise.