Nutrients

Hi I’m trying to get my plants strong and thick...I’m using GH one part nutrient the question I have is how much armor si do I mix in a 5 gallon bucket, the instruction calls for 1 to 2 teaspoons per gallon but my stems are still weak and this is my 3rd go around following the instruction and the plants are skinny going into the flower room and I veg about 45 day in soil....all I get is tall plants with flimsy stems and skinny stalk...