i dont know how you could increase the thc levels on a floro grow, floro's have such a low light intensity that you would need a lot of lights, with a lot of watts, penetrating the plant all over. the higher the light intensity, the more trichome development there will be, so my advice is to pack on the floros, and get them as close to the plant as possible. pLus, if you want to grow a majority sativa plant, ur crazy. Sativa's are soo bushy and big, a floro couldnt grow a sativa worth a damn!