My seeds sprouted a few days ago and I noticed today that some of the cotyledons are turning yellow at the tips and curling. They're all in jiffy pellets inside a rubbermaid lined with tinfoil and have tinfoil laid over the top of the light so it kinda looks like a tinfoil tent. The ends are not covered so they have some air flow. Im using a old aquarium T5 light fixture that's I believe 24" with 2 bulbs. The plants are about 2.5 inches away from the light. They looked great this morning and I decided to mist them, which was the first time I did it and put them back under the light. When I checked them a few hours ago I noticed how the leaves looked different. Ive read a few things saying I could be over watering, but I dont think I am. I only add water to them when I notice the jiffy pellet turns light brown.They're under light almost 24 hours, I only unplug when I go to work and my girlfriend plugs it back in when she gets home a couple hours later. So what do you guys think the problem could be, and what should I do to right it?