I would not try to increase the lighting except for duration. (If algae appear's,, decrease duration).I believe T5 bulb's will quickly make lack of CO2 apparent, Plant's falter,algae will take advantage of the inbalance, and also require more than just the flourish comprehensive.
Growth in low tech tank's is most often measured in week's, month's in my expierience.
I agree with this. It is important, also, for a low tech to be even more heavily planted from the beginning because of the slow growth. Get plenty of anubias and different types of java ferns. Plenty of moss. I love low tech tanks, so easy and stress free.