It kinda sounds to me like your giving it too much food, just the soil by itself can feed for months, also you CAN do 16 plants, but your gonna want to flower at about 6 inches so they don't get so big that they steal all the light from the smaller plants, you would also want to cut off most of the branches so your just growing single main colas ( kind of like doing a SOG grow). Try to simplify your grow, When I first started I also went nuts on all the stuff you could get to add to your fertilizers that touted all sorts of crazy shit. In the end a basic 2 part fert, some PH up and down, superthrive once in awhile made things grow like mad. These plants are weeds and do not need to be smothered with care and special meals all the time. Its cheaper to use less too.