Another approach

At the risk of offending hydroponic equipment dealers I am doing another post on building your own system. In my early years of amateur radio we built many of our own radios to avoid the label of "button pusher" that was applied to those who purchased all their equipment. I guess that habit is going to be hard to break. It is, however, hard to describe the satisfaction of making a contact half a world away on a two watt radio and antenna that you assembled from basic components. I find the same satisfaction watching plants flourish in a system I built.

This system consists of a reservoir constructed from a 18 quart covered storage tub, a submersible pump, airstone, a length of PVC 1" pipe with end caps, net cups and a fill/drain fitting and 1/4" tubing to feed each cup.
The PVC pipe is connected to the pump which rests on the bottom of the reservoir and is supported on top by the cover. The PVC pipe is drilled and fitted with lengths of tubing which are then fed to each individual pot. (If I am not using each pot, I simply fill the empty pot with pellets and run the unused tube to a pot that is being used.)
In operation the system is filled with about five gallons of nutrients, which can be measured with the fill line on the reservoir. The distribution tube distributes the nutrient solution to each individual cup and the solution dribbles through the medium and returns to the reservoir. This action, coupled with the airstone, aerates the solution. Eventually the roots will grow down to reach the solution and growth will be fantastic . The bubble action provided by the airstone and falling solution creates a nutrient rich mist within the enclosed reservoir which further benefits the plants. I have never seen any indication of root rot using one of these systems.
Nutrient changes are made using the fill drain fitting which also serves to display the solution level, and levels are maintained using the fill port on the cover. Flushing the system is a breeze. Drain the nutrients and fill with whatever you use to flush, like Flora Kleen. Run the pump for an hour and go read a book. Drain and refill and you are back in business.
When growing lettuce I operate the pump continuously; with other crops I operate the pump only during the light cycle.
Simple, effective, cost efficient and "homebrewed".