N deficiency or nute burn?

[vpshd]

Most of the plants that i have indoor are having the same problem: bottom leaves start to turn yellow on the tips and slowly extends to the back of the leaf and sometimes that leaf even dies...
I found that this symptom can be a N deficiency or also a nute burn. I am feeding with a 10-3-7 fertilizer.
The top leaves look very nice...
Can anyone figure out whats the problem?
Here are some immages of the leaves:

 

[David Bowman]

It looks like it's either nutrient burn or over watering. I would back off on both until the soil is quite dry and then giver it only water next time to see if that helps. The existing damage won't be repaired but you should start to see that the newer leaves are not getting burnt at the tips as they get older.