Help W First Grow

This is my first grow. I'm pretty sure the problem is overwatering, but I wanted to see what everyone thinks. I have no more seeds so I need to get this fixed if I can! My "grow room" is hot and doesnt have good ventalation, but its all I have for now. I know the conditions are far from adequate, but I'm trying to work with what I have.
So anyways, 3 of 13 plants are showing yellow leaf tips, it's funny that its only the ones that have fallen behind in growth compared to the others. This morning the soil was very dry so I gave them a good watering per instructions I've seen on grow videos - watered until it drains out the holes. I have been just spraying the top of the soil until today when i poured spring water on them from a bottle. Same water I've been using. Here are my grow conditions:

*4 26w cfl 6700k 3 inches away from plants with aluminum can reflectors
*miracle grow moisture control in styro cups with holes cut in the bottom, I also cut a lot off the top so they are only about 1.5 inches high so the soil on the bottom doesnt turn to mud.
*"room" (box) can get to 80-90 degrees, but its been 2-3 days since they came above the soil and this is the first time I've seen this problem.
*using 50-75% recommended superthrive. Only 1 drop per ten ounces.
* small fan in box blowing on plants and lights.
Thanks in advance for your help, I only need to get through 2 more weeks then they are going outside when I move. I know my conditions ****, but they have been growing like mad, seems by the hour sometimes. THE PIC mj (incase the image doesnt work)

By the way, I'm laying off on the superthrive for a while. I'm sure they have enough in the soil since the plants are so small. the soil does look and feel overwatered, but I'm learning and I can't narrow it down to too much nutes in the MG, heat, or overwatering.......

Do you ph test?

Hey mogie, actually no I dont ph test, this is all I could afford. I thought spring water would be adequate. Could spring water cause yellow leaves? They grew for 3-4 days just fine with no yellow.

Your plants are way to young for any nutes. They should be at least two weeks old before you start any thing. In your pic the two leaves that are turning yellow are the stater set, ( I forget the name of them ) any way they die off they have already served there purpose. In the pic they only look a week old.

your over reacting

Thanks for the support Doobs, it's just that if I'm doing something wrong I want to know. Seems like this moisture control holds a lot of water. Does anyone else water until it leaks out the holes in the bottom of the pot? The soil was almost totally dry to the bottom when I did this.
BTW - they're not a week old, It's been exactly 5 days since i put my seeds in a paper towel. 3 days in soil. My others are twice as big. Thanks for your replies!

remember seedlings are very sensitive, trying to fix a problem could just cause one. if your soil retains too much water add perlite. dont worry but watering too much at one time, just make sure you dont water too often.

i guess you're right. they're sleeping now and the soil doesnt look as moist. A little dry on top and moist underneath, not too wet. I'll see how they look tomorrow. thanks.