3 Week old Plant Issues (First timer)

I got some seeds from a friend of some good stuff that he grows. I have it under a small light, i believe its a 100 watt CFL with a 8" reflector on it. (I know I wont get the most yield from this way, but im just trying to get used to the plant and methods first)

I have been having a problem with Gnats. A big bad problem.

I covered the top of the media with cut up notebook pieces to stop the gnats from getting down into my soil. (This seems to have worked, to the eye)..

But shortly after this started happening the leaves began to brown and things like that..

I clipped the extremely dead leaves, and now more leaves are getting dark brown spots.

I am barely feeding it miracle grow plant food. I have like 3 pebbles of the food in my media, I didn't want to over nute.

I just bought Ortho Flower Fruit & Vegetable insecticide.. It is said to be safe on all plants, even during flowering and kills over 100 different types of insects.

Would this be safe? Is this even the problem? Would I just spray the leaves, or the soil too?

(I just noticed before lights out that there are silver streaks in the soil, small white specks, and white fuzzy stuff at the very bottom of the stems)

HELP PLEASE!

Grimm

1st picture is the leaves before
2nd picture is after cropping off dead leaves

but now the leaves are starting to be the same..

Dr Grimm said:

I am barely feeding it miracle grow plant food. I have like 3 pebbles of the food in my media, I didn't want to over nute.

Click to expand...

They need food. The lower leaves are dying because the plants are feeding on them. You don't mention the pH. Be sure that the pH is correct before & during feeding.

check (closely!!!) the back of the leaves for thrips. they are very small, use a mag. glass. they do look at bit hungry too.....

Ok guys, I applied the insecticide GENTLY (I used a q-tip and brushed it on and rubbed it on the surface of the soil) I just woke them up from their nap. There aren't any gnats anymore! Hopefully they stay away. Now I can focus on getting them back to health!

I added a few more pebbles of the MG plant food. I know people say it sucks, and it burns the plants a lot that's why I didn't want to over-use it. I really have no other resources, I don't have much to spend on this at the moment.

Will this food work? Or is there something else that WALMART/Kmart has?

How much is too much? They have it measure is sq ft. And im not a mathematical person, I wasnt sure how to come up with this # for my media. So I tried to spread the pebbles lightly.

Thanks for the help guys, I have become some-what of a fanatic with this plant, it is really cool to see it grow every day.