Hey, man, I have been doing a lot of experiments with Air or Oxegen, and I have determined that adding additional oxegen makes a tremedous improvement in speed of growth. I did a 6 plant bucket with one small air stone and a 2nd 6 plant bucket with two big long air stones. (by air stones I mean the kind you buy in the acquarium department) My tank with the 2 big air stones had plants three and half ft tall when the other tank was only 2 feet tall, from same species of plants. I highly recomend getting a strong air pump, they make one with two connections and get the largest air stone, or 2, that you can add.