One of your major problem si that you are using low pressure pumps. The second is that you are using high volume spayers. Here is a link to some misters. They work much beterr than psrayers (the cheaopy grren, blue, and red garabage misters that Eral pots links to).
Misters:
http://www.dripirrigation.com/index.php?cPath=43&sort=2a&page=3
For even better performance use a medium pressure pump:
http://cgi.ebay.com/Iwaki-Magnet-Pu...cmdZViewItemQQptZBI_Pumps?hash=item35a595da37 This pump delivers about 25 psi versus the 2 to 5 psi that your pumps supply. It uses 90 watts. You do not need a large volume of water to be sprayed. The roots n merely need to be moist. My tube aeros spray 2 seconds per minute with low flow misters. No I do not turn the pump on and off. I use a timer and soleniod valve. The solenoid valve installed with a T fiiting sends the water back to the resrvoir all but 2 seconds per minute. Aquarium pumps are made to run 24/7. turning them on and off repeatedly shortens their life spans. I run the spray cycle the same at night not out of need but simplicity. The roots could easily go 2 seconds every three or four minutes verus every minute.