I rearly dont think any of those will affect the yield at all. just the plant growth. You can put the seedling under a 600mh hang the light a litle way up to make sure they dont burn and dry out.I've been having my lights on 24/0 while my plants are in veg and I was wondering if anyone has seen more/better yield going with 16/8, 18/6, or 20/4. I also just got a few seeds and was wondering if I can put them under a 600w mh once i transfer them into cups.