Yellow Leaves

I have 3 plants about 6 weeks old under 4 40watt fluoros. The tips of the leaves got a bit yellow then brown and now the edges of the leaves have a yellow border. I used some Shultz 10-15-10 plant food but I stopped because I thought it might be nutrient burn but now I am not sure. Also, my soil is a mix of miracle grow organic potting soil and perlite. Any ideas?

The miracle grow potting soil has time release fertilizers? Can you upload a pic or two?

The miracle grow time release fertilizers are actually released when you water. Thats why overwatering also causes nute burn.

A solution would be to just not water for little while.