idk man. im using MG. and im into the 2 week no problems. but idk if i need more lumens or not. because 1850 lumens X2 bulbs. but ya kno. its doing good for the 2 plants. no yellowing no nothing. the way i water my plants is with a squirt bottle. i spray 2 or 3 sprays around the stems of the to plants and they love it. i do that about 2 or 3 times a day. but i oonly have the lights on about 13 hours aday. you think if i went to a full 19 hours of light they will grow better???
I have no idea what my lumen output is, these lights came preinstalled in this fixture, but they're both regular 27 watt cfl's.
You may have something with the sparying there. Their first week, I only sprayed them and nothing else, then went to just watering fully every few days. And come to think of it, I probably just sprayed them way too often near the time when they started yellowing, and then made it worse by fully soaking them.
And for your lightcycle, 12/12 will put them into flowering, 13 hours will probably do the same. You need 18-24 hours of light to keep them in veg so they can grow before budding up. Also, the more light, the faster they will grow. 24/0 being the most optimum for fast growth, but it uses the most electricity, and thus costs more. Also your lights are gonna die out much faster if you leave em on forever.
I'm on 24/0 though, as I need these plants to grow as fast as possible, and be harvested by May.
I'm going to try just spraying my plants a few times a day. Maybe keeping the top moist with the spraying will keep the bottom from drying out, but keep it from being soaked also. I'm also going to add a bit of peroxide to the 2 really sick plants to test it out and see if it helps or hurts.
I'll post some pics of all of them in my grow journal, which is in my sig.