need help with small plant

hi
i have a small clone 3 weeks old. some of her leavs turnd light green the rest r ok i think.
is it n def.? or somting alse?
lighting 120w Fluorescent, soil
i feed her once a week with bio grow and alg a mic and one with wather ph 5.9
thanks and smoking weekend

she's pretty. um pH too low get that up to about 6.0 to 6.5...also may be an NPK issuse... you could put a little compost or dried out old cow bird or bat poop on the top of the soil to help get PH up and balence the NPK ...what kind of soil are u using? and whats the NPK of the nutes u have? thats three numbers on the bottle some place may look like this "13-13-13". also u wana trim away any leafs that are over 50% yellowed use a normal pair of sissors and cut at a 45 degree angle. hope i can halp ya good luck

hi
thanks for answering
the soil is regular soil from garden nursery but its a good one. the npk is 8-2-6 and 4.3 iron
i'll try what u suggest, looks interesting
the burned tip is for the ph or for nut def? or both?

thanks