That looks like Toxic Salts build up to me.

You over feed them with the wrong nutrients at the wrong cycle and the Ph is off so even if the nutrients are there the plant can't up take them or use them.

You need to flush 100%...watch your Ph and when you do feed them back with nutrients you need to start back at 1/2 strength one time then keep up with the cycle if life feeding for their age and what ever cycle they are in at that time.

With out more information that is just a guess....I bet I'm right about my guess though.
Zandor Reviewed by Zandor on . plant needs helppppppppppppp ok so these are pictures of leaves at the bottom of the plant, some of the bigger fan leaves are starting with orange to browning spots on them, and this sucks i cannot figure out wut it is, and i need a definate diagnosis so i can treat before all this becomes a threat, the lights arent the problem, im thinking maybe nute lockout, or mg defficiency, but ive added some epsom salt in water, and treated for like a week and no help for that so i dont know, i need them damn spots to go away, im Rating: 5