DN328
are you running all 12 bulbs??? Coz that sounds like an extremely high amount of light in my mind...
I personally run 4 T5-HO on my main (50G) planted tank and worked out a 4hr on / 3hr off / 4hr on schedule worked, but still required a fair amount of Co2 to prevent algae from taking hold...
I also took any plant trimmings and kept replanting them to help compete against the algae in the tank which finally seems to be balanced for my tank...
Anyway, good luck with your tank, and hopefully you dont give up