Someone sent me a private message asking what was the purpose of the controller bucket and the chiller.
The controller bucket has a a timer to initiate the flood cycle and float valves to turn off the flood cycle when the water has reached the proper height.
After 15 minutes of being flooded, the pump kicks back on and drains the water back into the nutrient reservoir.
The link below is a great 3d animation of a similar system:
The air stone deep water culture system you are talking about using is great for different crops b/c you can change the nutrient make up depending on the crop you plan on growing, but if you are growing multiple plants of the same variety, the multi-flow allows you to scale your operation up more efficiently. I have 18 tomato plants growing now, but the system is expandable to 48, all I have to do is add more pots! I don't need air stones b/c air is sucked through the root zone during the draining process.
I found a used aquarium chiller on craigslist cheap so I bought it. Its necessity is questionable and perhaps considered overkill by some, but I was worried about my reservoir temperature getting too warm, which will cause certain pathogens/diseases to more easily propagate. Another method of keeping the reservoir cool is by burying the reservoir in the ground, or during the hottest time of the growing season, adding frozen plastic water bottles to the reservoir.