Seedlings are very fragile and need to rest for for 4 hours minimum at night....too much light activity will cause them stress......Once they are established 24/0 is optional...The good thing about 24/0 is that you will have about 25% more grow time and more mature plants in a shorter period of time...But I choose 19/5 for the slightley lower electric bill and the fact that plants in Nature [and every living thing on Earth] all need SLEEP!
