Like [MENTION=11086]theMerchant[/MENTION] mentioned Pohl's xtra special and coral vitalizer from Korallen Zucht will help bring your colors back and then some on your corals. That stuff is specifically designed for ultra low nutrient tanks.
As far as the algae on the glass, dosing some form of bacteria will help as well. There are nutrients in the tank, just not in your water column. As your tank matures with more beneficial bacteria, then you'll notice less algae growth on glass, sand, and rocks.