Try to find some bigger pots and transplant them into more soil. A 2 gal container of potting soil per plant will make for a cozy fit. If you can't find something that big then atleast get them into something that holds a gallon or 2 lieters. I dont know much about those aero beads your using, never gave them a chance befor. Do the containers with the beads hang down below the grow box? If not then you should get them a bigger container to let the roots grow. My buddy had a plant thats been in a 32 oz cup since seed. We both started the seeds within the same week and mines 3-4 times the size of his. Atleast in soil, I believe, the overall height of the plant is usually represented by half of its roots underground. If you want to see some pics of my plant, there is a link in my sig. Those pics are almost a week old.