We just got our first windowfarm going, but it was not without a bit of experimentation, and in particular, getting the airlift working. We started by downloading the MAMA v3.0 design, and was eagerly looking forward to our windows going green. However, living in Malaysia we quickly realized that pretty much none of the listed components were available.
We went to the hardware and aquarium shops to find out what WAS available. To make a long story short, we did over 30 design variations and experiments over the course of two weeks, learning LOTS in the meantime, and below is what we currently have. As always, it’s work in progress, but at least it shows some variations that can be tried out.
The major realization I had after failing miserably in the beginning is that the core design principle in a windowfarm is basically “use an airlift to feed a series of water bottles nutrition and water”. Everything else is optional and variable (which it what makes this so much fun!). Here are the major variations we made, to the suspension and airlift. Here is the big picture of what it looks like right now:
There’s a tiny airpump to the left, and we found out that we HAD to keep it on the “low” setting. Too much air will disrupt the flow of water. There’s four bottles right now, and they are not screwed together. Instead the top of each bottle is cut out, and each bottle leads to the other. At the bottom we have a reasonably high and narrow bucket for the water and nutrition. As others have found out having a high pillar of water is key to getting the airlift to work, and this way it’s easy to refill as well. The end goal is to use this single airlift and bucket for the whole window. We’ll see how that works out.
We couldn’t find any of the suspension components from the original design, but got real lucky in one hardware shop (Ace Hardware in Kuala Lumpur) where we found a one-foot pot hanger. Our window also has a a metal grille (in Malaysia pretty much everyone has grilles for the windows due to breakin risks, perceived or actual), where three metal bars account for one foot. One bottle also turns out to be approximately one foot. So, put this together and you get what is shown in the picture. One end of the hanger is attached to the grille, and the other is put through a small hole in the cap. We also have a triangle cut out for the water to run out, so it doesn’t go through the hole for the hanger. Now we can easily put it and take out bottles. We also experimented with skipping the net cup for the plant, but I think in the end we have settled for having it in. Then we don’t need to duct tape the whole bottle, so it just looks nicer.
We then have four of these bottles in each line. All in all we should be able to put in a maximum of 36 bottles like this in this single window, and each is easy to put in or take out due to this suspension system.
The second major problem we had was with the airlift. We couldn’t quite find the components shown in the MAMA version, and there was just too many places where it could leak. A bottle also has too low of a water column to consistently get the airlift technique to work. After LOTS of experimentation with various designs (including using straws for tubing, which was awesome but leaky), and looking at how others have done it, we settled for a dead simple version: the T-airlift.
In the middle of it all is a T-joint. On the left we have air coming in from our airpump. On the right we have water coming in from a 3-foot soft tube. At the top there is soft tubing going up to the plants. We have taped the soft tube to the wall, which makes it straight enough. Because the tube for the water intake has a natural coiling effect, and is quite long, that is what keeps it down in the bucket, so we don’t need to tape it down or anything like that. We could make it even longer to increase that effect. I think that having a reasonably long one also helps in not getting the air to exit that way. Sometimes the air will push evenly upwards and into the water tube, but as soon as the pressure is released by the first water dropping into the bottle line, the air seems to prefer going up rather than out the water intake tube.
This system does not require the one-way valves, or needles, or somesuch, and allows for a high water column and easy adding of water. There’s no air leaking going on since the T-joint handles that quite well. It’s not as pretty as other versions, but this is in our basement (with window to outside, since we have a terrace house), so that’s ok.
So that’s it! Now we want to add more lines, maybe reusing the same airlift, and also maybe experiment with using a solar panel to drive the pump for the ultimate post-apocalyptic-nothing-works DIY experience.