okay so i havnt posted to this forum since 2012. since then ive recently purchased a fully established saltwater tank. currently it is stocked with 2 occelaris clownfish and a banded coral shrimp. my main concern is the previous owner didnt have any live rock at all in this tank, just a fluval c-5 power filter loaded with bio media as the main biological filtration. my question is, if i purchase some dead rock from ebay, can i just add that in? i really wanna liven this display up with some rock formations but if i buy 40 lbs is it safe to just rinse and add to the tank?