Tons of people do 24/0, and tons do 18/6, some do 20/4. I used to be a firm believer in 24/0 for the first two weeks but honestly I've latley switched to 19/5 or 20/4 for all first couple weeks, then 18/6 because the plants on 24/0 grew such a minuet amount faster then the 18/6 plants that it was hardly worth the electricity.