need help with my plant

my plant is 2,5 weeks old, in the last two days brown spots have appeared on both bottom leaves (the first real leaves not the round ones), i´m watering every 5 days, no ferts, using a 40 watt flourescent light(swirly tubes)3 inches away from the upper leaves 24/7, one week ago i placed the light too close to the plant and it burned the tip of the two center leaves of the second floor, but except for that the rest of them are looking perfect.
what could it be? is the light too close? is it the light cycle?
thanks for your help

 

Here is a picture

 

im not exactly sure what it is, but i do know it is NOT your light cycle 24/7 is fine up until flowering

 

heres another picture

 

i dont know what to do, she looks quite unhealthy, the light is now set at almost 4 inches distance, but now it looks like some of the new leaves are getting burned too. Thats the thing i dont understand, some of them look pretty good but some are in very bad shape. Look at the little yellow ones in the center. And the spots are increasing every day, compare todays picture with yesterdays

 

Do you smoke cigarettes around it?

Cannabis is unbelievably susceptible to a tobacco retro-virus (cant think of the actual name off the top of my head)

the virus can be caught through tobacco smoke, even through your hands if you fail to wash them after smoking a cigarette.

 

by the way, I can almost gurantee your going to have even more problems as the plant gets older, flourescent lights, despite alot of conjecture, are NOT growing lights, the light spectrum produced by flourescent lights is not what you need for growing....your plants will never live up to thier potential under flourescents, are much less likely to be female, and the yield (if any) will be much lower, since your plant is not getting the energy it needs from these lights, it also makes it much more susceptible to disease.

 

Could you have left water droplettes on those leaves, because the damage seems to have happened before the latest branches .

water drops act like magnifing glass on leaves, know 'cause I've done it...... and kicked m'self for it.

 

The soil you are using probably has too much fertiliser in it. Just be patient as the plants get bigger they should improve. As long as the new growth looks healthy (as it does) you should be OK. Try checking ph of soil.

 

What kind of soil is it in?

If the soil came with chem nutrients already added, that's your problem.

 

Looks to me like you spilled nutrients on when watering and not nute burn via ov er ferting as nute burn from excess nutes begins on the leaf edges then to tips.