Curing dead rock

[SleepyPirate]

So just a couple quick questions, I got about 60ish pounds of dead rock and steamed it at high presure for about 4 hrs at 600 Degrees. (I work with oil tankers and its enough to clean one out to eat out of). I then hosed the rocks off for about 10 mins to get anything off of it i could like sand and whatever would come out, I then put it in some water iv been taking out for water changes and added a prawn in a mesh bag with a fan and heater, its been about 3 weeks since I did that. Im just wonder what else i need to do and when i take shrimp out ect.. I havent tested or done any new water changes since just let it sit. Can someone give me a quick run down on what to do next?