I was wondering this last night as I was in each tote last night to pull out roots that were traveling and looped them around the main mass to help keep it there. I remembered your post about it so perfect timing! So the verdict is directly under? I was looking at one of the totes and I thought maybe the airstone was acting up cause it was so low, picked up the plant and it was boiling again. So in my head no surface agitation = less DO but your experiment has proved the opposite?