The Water Cycle

The central part of this whole project is to fully automate water going in, and water going out. First thing we need to deal with is our source (since we lack an outdoor tap). We also run the risk of running out of water (and being wasteful) if we’re simply letting it evaporate after it has already drained — so we’ll simply return our water back to the source container to keep a full cycle loop. I eventually settled with a covered plastic container for my water reservoir. I don’t have many still-water bugs in my area, but it’s always good to keep contaminants out.

Next, we need to get the water to-and-from the plant. I get to cheat here on the design a bit because I already had pumps from a separate project (food grade alleviated any concerns about oil or something contaminating the water).

Diaphragm-style and Submersible-style water pumps

The first “watering” pump (black) is a submersible aquarium-type pump that is also found in those tiny garden and desk fountains. Nothing really powerful is needed, and more power would probably be a hindrance considering we’d like to avoid the need for a separate additional voltage regulator. As for your spray nozzle, simply capping off the end of your hose and drilling a line of holes at the end will usually be enough to create a good spray.

The second “siphon” pump (white) is a primer diaphragm-style pump (and is not at all waterproof as it has holes in the chassis). The benefit of working with this style of pump is that it can “run dry” — meaning we can over-pump our soaking basin without risking damage if there’s no water to pump. The diaphragm is also fairly strong when pulling down an air+water mix through the filter — as opposed to the submersible style which is a lot more finicky.

Both source (top) and drain (bottom) pump hoses — a slight tilt will help direct drainage as well.

After this, we just need to add a few hoses and our water cycle setup is complete. Depending on what your layout is, you can direct your spray and siphon tubes for their best position ( I used helping hands to direct the shower flow.) Remembering our initial requirements to prevent FOD from going into either pump, a filter of some sort should be added to both the intake from the water source as well as the plant basin (I used a simple cheesecloth and rubber band over the pipe.)