Hydroponics (By Request)

Some of us were discussing hydroponics in guild chat today and, having some experience in that area, I am starting this thread which will involved re-posting some stuff I put up on the Internet on other forums some time ago. Also, some links. Feel free to ask questions, make comments, and add your own input. Here we go:

To start: This is a picture of a hydro tray that's been partially harvested:

You can see the fluid input to the left. You can't see the output drain that's underneath, draining from the lowest point of the tray. The tray is heavy-duty plastic filled with pea gravel for a growing medium, which we purchase in 50 pound bags (22.5 kg). The light fixture is recycled from, if I recall correctly, an out of business drug store (chemist, in some parts of the Anglosphere). The bulbs are full-spectrum lights for indoor plant growth.

This tray has Swiss chard, Beta vulgaris subspecies maritima, white stem varietal. The plants are over 30 cm tall.

This is a tray that's a little earlier in the growth cycle:

The light fixture here is also recycled. Actually, there's a lot of recycling going on here - the main supports for the trays are battered sawhorses and doors too damaged to use as doors but still suitable as tables for this purpose. The lights are supported by a metal fencepost from a dismantled fence held up by battered step ladders. (Much of this was donated by my partner in this endeavor who has an access to an abundance of such things, having owned a construction business for a few decades.) We did buy the trays, buckets, and tubing that carries the fluids and holds the plants to avoid possible contamination, and to ensure good condition. After all, we eat the produce.

More Beta vulgaris subspecies maritima, this time with a mix of stem colors. And one spinach plant on the left that's gone leggy. Sometimes, you get unpredictable results, especially since this is not the most sophisticated set up. So far, we've had much better luck with chard and radishes than spinach, not sure why.

This is one of the fluid reservoirs showing the in/out plumbing, the pump (submerged white cylinder), and the switch (black whatsit)

The switch is attached to a concrete-filled potable-water grade PVC pipe (the white vertical pipe next to the switch) so the level can be adjusted. The lower parts of the switch is a float. The upper limit turns on the pump, the lower limit turns it off, and it can be slid up and down to accommodate different levels in the reservoir. When the power goes on, if the switch is at the upper limit it turns on, then runs until the lowered water level brings it to the lower limit. The lower limit is important because this pump is designed to stay submerged, sucking air in would not be good for this system. It's basically the same design that runs a basement sump pump.

This is the reservoir as it usually is, covered and under the trays.

Yes, the picture is dark, and the bucket is covered with foil. That is to prevent contamination and reduce algae growth. You won't keep it completely at bay since this is essentially a bucket of food, and lots of things can eat it. However, you want the fluids to go to growing YOUR plants, not random wild intruders.

And.... this is what happens when things go awry:

This is an algae mat covereing a fungal infection that wiped out an entire tray/bucket system. This can happen (obviously) and is a pain in the ass because that means tearing everything down, cleaning it all, sanitizing it and starting the tray over.

This is a very basic ebb-and-flood system using an electric-power pump to input the water into the growing trays and gravity to remove it. It's a cheap system, utilizing a lot of recycled stuff we had lying around although, as I mentioned, we did purchase new, clean stuff for certain parts. We're getting a harvest about once every two weeks at present. We use indoor grow lights, but as you can see there are also windows supplying natural daylight as well. The grow lights are essential during the winter as our short days do not provide enough light to sustain growth. It's not as productive as a highly tuned, precisely calibrated system but then, we wanted something that didn't require constant attention. We put about 1-3 hours in per week, and can leave it unattended for 4-5 days at a time (with mature plants, up to a week). We were aiming for a low-maintenance set up rather than pushing for maximum production of plant material.