Please Help me with DWC

When we do DWC, we start plants as clones in a home-made cloner similar to an ez-cloner, as soon as they show some root, we put them into 3" net pots with hydroton, and put the net pots into a setup that uses holes drilled into 4" irrigation tubes with sprayers (I can describe better if you're interested), once they are at least 6-8" and have the beginnings of a nice root ball, we move them to 'best plastics brand 27 gallon strong boxes' (they are black, quite sturdy and have a yellow lid - we get them at Home Depot), we drill usually 12 holes (3" round) in the lid of the strong box, fill with water to about 1/4"-1/2" below the bottom of the net pots, add veg nutes to between 1000-1400ppm, and run one 250 liter air pump for every 2 or 3 'strong boxes' with 4 or 5 airstones in each box, and we see about 1/2-1" per day of growth (we see better growth in the sprayer/ tube systems and only use DWC for mother plants that are going to get to be too tall to use in the sprayer/ tube systems). As the plants grow, we space them out more and fill in the empty holes with plastic beer cups to keep the light out.

We tried it with the $10-$20 air pumps and had problems, so we only use the bigger air pumps (the 250 liter one runs somewhere between $60-$85).