I've always grown under 20/4 but this last round i decided to try 24/0 to see what happened if anything. It could be just me watching them so much but i think 24/0 seemed to take them longer to get bigger.Growth seemed slower for some reason with constant light compared to a 20/4 schedule and it definately didn't make them any bigger.going back to 20/4 for my new round of younguns.