Ok so as the title says I got a couple plants that are 3 weeks into veg. I'm using Fox Farm OCean Forest soil and they've been under 24/7 CFL light since they popped outta the ground. Temps vary from 68-75F depending on the time of day. To water I use bottled, distilled water that I purchase from the store. A week or so ago I noticed my leaves turning yellow, starting at the tips and working it's way back. This only was happening on the older growth (in the pics you can see the leaves that I am referring too. They are the dead ones towards the bottom of the plant.) This, as you can see, happened with both plants at the same time. I figured it might be an N deficiency as they were about two weeks old and I had yet to feed them anything but straight water. So I mixed up 2 tsp of Grow Big into my gallon of water and watered them. It seemed to help for a few days as the new growth came in green and wonderful and the yellowing did not progress further than that. Fast forward to yesterday and today and it seems to be happening again. Moreso on one plant than the other as you can see in the pics. You can see in the relatively newer growth (and the biggest leaves) that it's starting to yellow up. I just snapped these pics a few minutes ago while I fed and watered them. This time I mixed up 3 tsp of Grow Big into the gallon and gave them both a half gallon each. I'm assuming this in an N deficiency and will probably go with it unless someone comes in here and points me in a different direction with a different idea. I would appreciate any input on this, guys. Thanks! The first plant is the first 4 pics and the second plant in the last 3 pics.