As for providing a place for benefical bacteria etc live rock will do just as well in pitch black as it will under MH lights. However foks also like to see coraline algae etc grow so therefore you do need somewhat decent lights and in most cases a regular NO flourescent light of proper temperature rating (10k) will provide sufficieint light levels to get coraline growing. I would not waste any energy rubbing rocks together.....Coraline will grow when coraline is ready to grow. YOU can probably set there and run 1000 rocks until they are nothing but dust and if conditions are not right for coraline its not gonna do a thing. If there is any coraline in the tank now it will spread when its ready. Ensure temps are good, and all other water parameters are where they shold be., I like to run calcium and alk at the extreme high end, and keep my ph at 8.3-8.4 or so and my coraline grows just fine.