My experience with airlift goes back to fall 1983 when I worked in a pesticides lab in Ireland. Distilling hexane. YUCK! Stinky boring job.
I was just amazed by the air bubbles going slowly through the cooling tubes on the distillation apparatus. There was almost total hold up of liquid as the airbubbles slowly went through the clear plastic tubes. I am not sure exactly why but it reminded me of the “perfection” that is in the krebs cycle.
It was 4 or 5 years before I put this to any use in a coffee jar vacuum pump. That was replaced by a combined tromp and airlift pump (the pulser pump) which also depended on almost exactly the same physics as you are using now in window farms! I found the pulser effect totally by accident. If I had not found it, I am sure I would have done something very similar to the “biofueled pump” (without biofuel) next. In fact, I did use the pulser pump to pump water from a 50 gallon barrel in a very similar way way back then. I just found the combination of tromp and airlift more adaptable so i stuck with it.
Anyway, I just put some videos on youtube that I think can help window farmers a lot. I do not have a windowfarm but maybe you can adapt what I show and incorporate it into your experimental systems.
The bio fueled pump might be too slow for a windowfarm, but anyway, it is here
http://www.youtube.com/watch?v=-y1p2pZaYTM You can power it with an aquarium pump too and that is here (But then it is not biofueled anymore)
http://www.youtube.com/watch?v=G6pfE_IxVgQ It should be able to pump to 20 or 30 inches but you need the you tube to go down that much lower if you pump higher.
My little experiment with the t-joint and airlift pump is here
I did not produce any figures but if you see the videos, I am sure you can see that the aquarium pump powered things pump fairly quickly.
The biofueled option has potential to spread the windowfarm concept to places where they have no electricity.