Ide say this one will be mixed based on personal preference... I used to do 24/0 and it worked well. but some say 18/6 is better because it gives the plant some time to sleep. some say 18/6 is better because it gives the plant a chance to respire without the stress of photosynthesis at the same time. But great results have been had with 24/0 lights, plus it will grow a little faster I've noticed.