I have the Water Farm 8-pack with two additional units I simply added in-line. PROPERLY set-up, the controller and the additional grow modules are a continuous circulation system in addition to the timed drip irrigation. They provide a small, single port pump to keep on 24/7. This runs an air tube (like the water farm's tube) but only this intakes water from the first module. It is inside the controller (lower big bucket) which in turn takes from the second, and so on... all the way to the return end of the controller (front). I like the idea of the tee to better drain the whole thing (bitch as it stands), but by changing any elevation of the reservoir or the modules will defeat the natural gravity and gentle circulation, and it won't circulate properly. My whole system is supposed to completely circulate (8 modules, member I have 10) in 4 hours. That seems about right. The system is designed to be at the same elevation to work effectively. Inexpensive way to get the job done. I added a valve between the reservoir (top) and the controller (bottom). Closed, I can mix in the water, pH, nutes, etc. in the top (res) and hold it. Otherwise, it will start to fill the controller as the reservoir always keeps the controller (and thus the farm modules) at a constant minimum level. I know the exact amounts of everything, and can add 13 gallons of treated water in a moments notice. Once mixed, open the valve and the rest is pretty much, maintenance free for a week or so. Even the single, stand alone units work quite well. I LOVE these.
