Yes cook rock kill everything and anything that is good on it all he really needs to do is lights off for probably a month and weekly water changes. pluck as much HA off as he can and keep at it. It sounds like this rock maybe used rock but tank is newish Jan 2010 or so from. I do not cook rock as you kill everything that is good and you might as well start with dead dry rock, if you are going to do that. I did cook some rock by accident heater stuck and the temp probe I had was not working right so I put a good old glass temp thermometer in and found that it was up to 87 degrees. good thing I was just starting my cycle out or I would be upset. I know allot of people cook their rock I do not, I let nature do its thing and I pluck. Maybe use a bit of boiling water on the worst spots it will affect about 1 inch around where you use the boiling water, but it will kill everything it touches and leave some of the good stuff behind.

Bill