from my understanding, 8 hours seems to be the common/mean photoperiod. but i have read of people who go anywhere from 6-12 hours
and i had a 10g petsmart kit and 2x 23w spiral CFL bulbs made some pretty large temperature swings in such a small tank. i would recommend trying out the 13w bulbs if you can find them.
also, whats your substrate now?
Ya, I've had a hard time finding the 13W 6500k CFLs. I may try again tho as they do seem to really warm up the water.
Right now I just have basic black gravel. I purchased some flourish liquid and plant tabs to add in once I get the plants.