what i have done in the past worked really well it requires,2 dual outlet pumps per dwc container.i ran 12 inch strips at the bottom like u have done,and at the verry top of the container have drilled 2 1/ inch holes in between the net pots.picked up some of the smaller one inch true blue air stones,those sit about 6 inches deep from the lid down.that way u have the 2 at the verry bottom keeping the water moving and 2 that are pretty much your main source of oxygen for your plants.