You cannot calculate light intensity of the incandescent "equivalent". All tank lighting crude guesstimates are based on fluorescent normal output tubes. You must use the rated wattage of the tube. Then if you want to hedge a bit, you subtract a bit due to light wasted from restrike in the coiled tube. But they are still effecive lighting for small tanks.
So should i go with the Co2? If i dont need it i wont use it because i dont think i have room in my tank for a reactor. Does it just make the plants grow or does it do more then that?