you most likely can get away with the lighting you have. It's better to have moderate light versus too much! Trust me on this, you dont want to deal with algae! the general rule is 2wpg with stock lights, t8 bulbs with a poor reflector or no reflector. 1 to 1.5wpg with a good reflector. I personally use 1wpg but I have a very good reflector that I paid a pretty peny for. I dont get algae and my plants grow well. I think its better to have an algae free tank and have the plants grow healthy than try to tweak the wattage for max growth.