I wouldn't do anthing to the DYI rock until it's cured and ready to be placed in your tank or sump. At that point, you really don't need light for the bacteria to start growing, just a couple LR's to seed with. However, for coraline algae to start growing, you're going to need some kind of light. It's been my experience coraline will grow under almost any light. My plan is to put the DYI rock in a new tank I've purchased when it's ready and bring over a couple pieces of LR from my other tank. I would think the temperature would need to be regulated as well if you're planning to start seeding the new DYI rock. Throw a couple pieces of PVC in the tank while you're trying to seed it for coraline. For some reason, coraline will start growing on that first. Many folks have suggested using a toothbrush on your LR to release the spores. I have done this before, so I would agree with this. Unfortunately I had some Aiptasia and it also spawned a whole new outbreak.