green on gravel and rocks

[tang daddy]

looks like cyano bacteria to me. You have a couple options I wont really go into detail however you can:

shut off lights for a few days
do large WC
lessen the feeding
Antibiotic treatment like use bluecross red slime remover,or chemiclean
add sugar

The last two are pretty good however if you have any filter feeders I would not go with antibiotic treatment.

I like sugar the best as it's not harmfull to anything I used 2 tablespoons per 50g and after 3 days did a 50% WC.

good luck, Chris