Need help tips turning brown please helppp first grow

[Gare0440]

I,ve been growing my plants for about 4 weeks now. I have 2 plants grown from seeds that seem to constantly get the same problem. every time a new set of leaves appear and start to expand up the ones below start to slowly rott from tip in till there dead. they look burned with brown speckled spots slowly creeping in towards the stock, but its not possible because the tops are beautiful until the next layer comes. I,ve talked with people and they say it was a nutrient defiency, probably with nitrogen. I switched my soil from just regular compost to Black Gold potting soil yesterday as well as bought some Vitamin b1 nutrients to give them. I'm not sure how to solve the problem? my setup is in the corner of my closet and maybe its not getting enough fresh air because the air gets stail being all cooped up or what? please help ill get pics asap

[Gare0440]

here they are

[caregiver420]

You're not the first to deal with this this. Sometimes it can be difficult to pinpoint just what it causing it. Here are some resources I found:
http://boards.cannabis.com/basic-growing/92499-help-brown-leaf-tips.html - Another post in this forum
HOW TO HANDLE TIP BURN (http://www.schundler.com/tipburn.htm) - random website, not cannabis specific.

[mainegrown]

read the link in my signature that says "Plant Problems: Read First" that should help you isolate what MAY be wrong. if that does not work then fill out the troubleshooting form in the plant problems section of growing info..
-MG

[mainegrown]

and i think that you have 1) too little light for them to grow.. and 2) not enough nutes for them.. get at least miracle grow all purpose plant food .. just a guess not an expert..
-MG

[MARlJUANA]

looks like lack of nutes and light, try topping aswell to promote new leaves to grow.. the more leaves it has the more light it can absorb.