> is it possible for you to open-source it?

Absolutely, I’d like to work towards contributing useful things to open source gardening technology. Once I have something useful to put into the world I definitely will.

> Does it depend on daylight?

No, this particular system is totally isolated apart from fresh air pulled in to regulate humidity and temperature. The lights are the most expensive aspect of the system by a wide margin, but they do work extremely effectively. The plants are very happy.

I have an older iteration of the system working in an outdoor greenhouse without artificial lighting. It uses fans to regulate air temperature and humidity, but it gets light from the sun. It’s doing fine so far, but the temperature is still relatively lower so growth is slower than in the tent. I’m excited to see what the results are like over summer.

> Is water/air recycled?

This is an interesting question because at the moment the answer is no, but I have the beginnings of plans to recycle the water. I use a reverse osmosis system to feed into the system gradually (this ensures my water sensors provide reliable readings), and I’m fairly sure I could add a secondary tank to drain old solution into, filter it, and use it as the source for the feed into the RO system and then back into the active tank. Though it’s not necessary now, I think that level of efficiency could be incredible.

I’d love to be recycling nutrients as well. I know there’s plenty leftover when a grow is done, but I can’t know what the ratio of each nutrient is in order to rebalance it for the crop I’m growing. I’m sure some growers are able to do this, but I have a feeling it’s a bit beyond me. It seems like a job for a mass spectrometer. That’s possible to DIY in a sane price range, but I will likely need to wait until my kids move out to take that on. I do love the idea in any case — utilizing all of the nutrients and reusing them when possible would be a major accomplishment for me.

> What is the reason behind you making this?

There are several reasons. One, I eat a lot of greens and they’re getting more expensive. I kept a sheet in Soulver (a sort of natural language math program) which outlines a cost breakdown of a head of lettuce grown hydroponically vs from a store. It eventually hit a point where I could grow it for less than I could buy it for, and it justified jumping in and making it happen. My ROI has worked out fine, so the sheet was correct and it’s not crazy to grow with a system like this (so long as you don’t mind the maintenance, harvesting, trial and error, etc). It has actually worked in favour of growing it myself quite a bit more since I first started and hasn’t shown signs of tilting the other way for a while now.

Two, I love learning. The more I learn the more reasons I find to be in awe of the world. Seeing the way the plants grow, understanding the chemistry and biology of the system, accomplishing new things with technology — I find it incredibly fulfilling. It shows my kids that the distance between here and making something interesting or useful happen is simply doing it. First we had an idea, then we had real plants growing almost magically in a system built from scratch. All of that is awesome.

Three, like you I see some instability in the world and I want to have a grasp on how I might ease tasks like finding reliable nutrition. I have bags of fertilizer because they’re not terribly expensive and they can help generate good nutrition quickly, easily, and very reliably. Something like the kratky method can actually work really well even without stable power, so long as light and temperature are reasonable. I also have a lot of seeds for sprouting, as they’re an incredible source of easy nutrition in emergencies too. I don’t really want to need these skills for that, but I do want to have practical skills for producing as much food as possible if something were to happen.

As far as open sourcing goes, I hope to get a sense for how easy or difficult it is to get up and running with this stuff once I can get it in my friends’ hands. I plan to add a crude web interface for managing environment and automation parameters, and I’d like to figure out a way to sensibly scale out the system. For example, not everyone I’ll be giving it to cares about pH or EC, so they don’t need those components. I could simply not solder things onto their boards, but I’d rather figure out something like using standoffs to join the boards in a stack and gradually add features that way. Kind of like hats on an arduino I guess.

As I iron this stuff out I definitely want to put it out in the world. At the moment there are so many superior options in ecosystems like raspberry pi, I feel like I’d be wasting people’s time. I do think a pi is overkill (though potentially complimentary) for this kind of thing though, and the power of a connected microcontroller with MQTT and simple RPC services is way beyond what most people expect.