I’ve just about finished construction on a 2-column windowfarm, and I am just waiting for my seedlings to get big enough to put them in. I’ll post some pictures when it’s up and running. Anyway, I have some comments and reflections on the “official” instructions and parts list.
So, I followed the instructions pretty closely except for on two points: first, my windowfarm is suspended from a free-standing frame on casters (which doesn’t really affect anything), and I used a t-joint for the airlift system. The t-joint (a.k.a. t-valve) design is really simple and easy to install and use, whereas I found the method(s) outlined in the instructions to be really complicated and, frankly, intimidating. The fact that the size of the check valve included with the air pump determines some of the other parts is pretty inconvenient. Anyway, I hope the instructions are changed soon to include this more user-friendly design.
Speaking of the t-joint design, there are some issues that I ran into with parts. Mainly, I bought a t-joint off the Petco shelf with all three openings the same small diameter. It’s made for three of the standard 1/4″ OD tubes that come with the air pump. The problem is that this makes a bottleneck for the flow of water. At least I think it’s a problem. Brian White say’s that the airlift tube should have an ID of 1/4″ for optimal performance, and he seems to have done his research. I ran the 1/4″ OD aquarium tubing from the reservoir bottle to the t-joint, and from the t-joint up to the bottom of the 3/8” OD 1/4” ID rigid tubing from the parts list (McMaster.com #9245K17). It works, but maybe it would be better if I had bought a wider t-joint and used wider tubing.
Speaking of things that could work better, there’s the Petco pump (#9902). It’s not adjustable, as far as I can tell. I guess I can add a little adjustable valve in the airline, but if I throttle it that way I’ll be wasting energy. I think an adjustable pump should be recommended.
Then there’s the tubing. Two kinds of tubing on the parts list reference McMaster part numbers, but the 3/8” ID flexible vinyl tubing for some reason does not. Now, McMaster has a ridiculously extensive selection of tubing, so we should be able to find one that works. I used #5103K36 (Chemical-resistant Clear Tygon Tubing, 3/8″ Id, 1/2″ Od, 1/16″ Wall Thk). It was okay for joining the two long pieces of rigid tubing, but it was not flexible enough for the top, to curve down into the top bottle. Technically speaking, the “bend radius” is too big. Maybe #5231K185 (Clear PVC Tubing Chemical, 3/8″ ID, 1/2″ OD, 1/16″ Wall Thickness) would be better.
Chains. I think the ball/bead chain is a good way to go, and McMaster was a convenient way to order it. Weirdly, though, the part number on the parts list (#3606T16) turns out to be stainless steel chain, whereas in the instructions photos it looks like they’re using plastic. It’s not important, but what’s up with that? I also ordered the specified couplings (#3606T41). They are listed in the McMaster catalog as being the same size as the chain, but for some reason the chain does not fit through the center hole. I had to widen the hole. I’m not sure what to suggest here.
I think that’s everything. I don’t mean to complain; I think the design is great and I really appreciate having access to it, but I want to help make it better and easier for windowfarmers who come after me. I hope this post is the right way to give this feedback. Sorry it’s so long and boring!