Why does my plant look like this, while the over thwo look like that? I put up info

-They are 4 weeks old
-My soil is a Miracle Gro Organic Mix then I mixed in Pearlite, there in 4 gallon pots
-Ive feed them one time last week and the week before that with Expert Gardener Plant Food i did a 4th of the required mix and put it in the water
-They are under two 25watt CFL's on a 18hour on and 6hour off cycle
The in the green pot and the one with the straw are doing pretty decent and looking ok i think but one of them after i transported it into it's main pot the next day the bottom leaves had these grey spots on it and the tips of the two top leaves are brown and black, curling up. does anyone know what this means? Is it nute burn or bugs? And if it is bugs can they spread to the other plants? Help would be greatly appreciated

the plants are too young for added nutes. water with good pH water and let them grow until they are "plants"

thanks, so thats why their are grey spots to right? cause i didn't think nute burn caused that

Yeah, I definitely agree with four20seven. That is classic start of nute burn. The tips burning and yes the grey spots are a symptom of too much of a nutrient, but most likely the over feeding is blocking something else. Bottom line you are doing fine just give it a little flush and give it straight water to get rid of most of the nutes. Your soil will provide most of what the plant needs for a while. I have used supertrive and some rooting stimulators at that stage, but never any NPK nutes. I actually forgot about an ez cloner growing 20 clones once and grew to about 2 feet in a couple months before I actually took them out off of water and light amount of clonex. They weren't that bushy, but point being in vegetative stage you really don't need many nutes until they get about 6" and you can give them some my favorite Grow Big or anything with nitrogen.

Anyway I just wanted to re-confirm this as I know I have had my troubles diagnosing my babies.
Good Luck!

thanks ilikerolls i stopped giving them nutes and they are lookin better but good looks for the help