Supposedly one of the best ways to 'cook' rock is exactly what you have planned. Heat, flow and just top off to keep up with any evap. You don't need any light or water changes. Any bad algae will die off as it is eventually starved of light and food supply. Only other thing I would add would be a skimmer. I did this with some problem rock I had for about 4+ months and it was the best thing I ever did to kill off a bad batch of dino's and other algae.