I've never seen BGA before is this it?

oh yeah thats definitely it. Its caused by low nitrate levels and lack of water circulation. Ive gotten rid of mine by getting a syringe and squirting hydrogen peroxide on it until its gone.

clean it off the rocks the best you can and black out the tank for a few days to be sure its gone. It will only be contained to just the rocks for a short time, if you leave it soon it will be on everything and much harder to get rid of.
I left mine a bit too long and it took 3 hours of plant cleaning before i blacked out my tank rather then 15 min if i had done it sooner

peroxide is a good idea but it wont fix whatever is causing the bga in the first place, nor will a blackout of course but with a blackout you can be sure you havent missed killing any.

http://www.theplantedtank.co.uk/algae.htm has a good description of what to do and possible causes

good luck.

Geoff

I know its low nitrates. I actually look over nitrates a lot. I'm gonna black this biatch out.

well spot treating worked for me so....its just alot easier to try that first then to do a full on black out if you dont have to. My bga never came back once i did that and got my tank balanced out.

those rocks look sweet, with the pearling and all.