You should really alternate your sump light with your DT... and I think 12 hours is a LONG time for you DT light if your talking 2 hours actinics, 8 hours day, then 2 hours actinics, Id cut my days down to 4 or 6 hours.... it will help with the algae...
and running your fuge light on an opposite schedule should help keep your PH stable which should help with the algae too...