http://www.thermopedia.com/toc/chapt_g/GAS-LIQUID_FLOW.html
Shows you some pictures (lower in the page)  and explanations and charts of how the different flow types transport water.  It also has some pretty mean (to me) calculations to help estimate achievable flow rates.  I do not know how well this can transfer to pipes round the 4mm, 5mm, 6 mm size but maybe it does.

Anyway maybe some people could number crunch and see how well it tallies with reality?

Also the how high can it go competition is still in effect.

No prizes but you might be famous on the internet for a day or two. Especially if you get 35 ft high or more pumping in the competition!  Everyone thinks 32 ft is unbeatable  but I am pretty sure they are mixing things up.
Here are the basic rules

Anyway it is a fairly cheap experiment if you do it. See my video below
Here is my version pumping to 13 ft high (over 3 meters)l

Failure is more interesting than success in our community.

In the windowfarms community, no design is final. Rather, we are constantly evolving the designs to better performance standards. They evolve because WE LOVE FAILURE.

You can think you have a brilliant design but, like the Titanic, most designs are subject to failure at some point and it’s only when you see how your design performs throughout several seasons and under unfavorable conditions that you learn its true merits and shortcomings. We are fascinated with merits and shortcomings. Distinguishing between them is the core of what we do.

In our community, value comes- not from having the idea that works- but from BEING A GOOD TESTER.

@ajinil is one of my favorite pioneering testers, who is trying growing strawberries year-round in a snow-laden environment with no supplemental lighting by simply supplying flowering nutrients. So far, he has kept the plants flowering for 9 months!

Innovation can be painful. Death brings moments of revelation for windowfarmers doing R&D-I-Y. Ok. So I was only fake crying in the image above, but I was super bummed about losing my okra plants. After letting off a little steam, we were really able to take inventory of issues from this die-off. Ultimately, this was the last version 1 system we built after determining that nutrients just plain like to clog both water pumps and drip emitters as particulate matter builds up over time and clogs pathways. Failure also motivates progress. This is when the airlift technique started to seem a lot more attractive and worth pursuing. Ian, Ania, and I got to work on tweeking the airlift to work for windowfarms just a few days after this came down.

The MOST interesting moments are the ones right before your plants die (=FAIL= YAY!). What was that edge condition you managed to rock for a while? What can we learn from it?

A mature plant’s root conditions are the best way to assess the workability of your windowfarm design.

I have a dissection table set up next to my windowfarms and as soon as I kill a plant (and trust me, I kill a LOT of plants with all of the frankenstein systems we have in the core team’s shop, where we test out the community’s ideas), I take it out, look at the root situation in the net cup and see what killed it. Were the roots massive and healthy right before they died? Did they dry out? Did I have spider mites? Are there any signs of rot? Were the factors that killed it particular to this plant or to the system? Would other people have this problem as well?

So maybe you want your windowfarm to thrive– totally valid. That’s why we give you two columns in the kits. One you can have be a control column, where you give your plants ideal conditions and allow them to thrive. Consider dedicating your other column to research. Take on an experimental conditions, fail, and report back!

-Britta