its an endless arguement about whether 18/6 or 20/4 are better then 24/0. People who dont like it, say plants need rest. People who do like it, say you get more veg growth. Honestly, I havent ever noticed enough of a difference to be attached to one, but I generally use 24/0 when trying to get as much veg as I can in a short period of time. I believe plants need light more then they need rest.