I only recently found out about Kratky Hydroponics .
I like its as an extension of wicking beds/container gardening.
Mr. Leon, a keen advocate for wicking containers shows us the Kratkey method at work in one of his green house.
Being cheap and adverse to being dependent on purchased chemicals, I looked into compost tea as a replacement for hydroponic nutrients, they have some history being used to good effect.
I anticipate starting my plants in a relatively large container, with relatively rich medium.
Peat moss and rabbit poop for instance.
This will make it more like a chinampas, the water providing some but no where near all of the fertility.
Salad greens, being expensive and pretty cold hearty seem like excellent crops for this.
I'm imagining a green house with an insulated northern wall lined with 55 gallon barrels, stacked two high.
The next row of barrels would be topped with half barrels, a large net cup protruding into the barrel beneath.
Arrange more of these in aisles, leaving minimum space in between.
Right now I'm cutting two icing bucket sized holes in each barrel lid.
I'm using what I got, and the ability to easily swap out plants might prove to be superior.
One bung in each barrel has a live willow cutting in it, to encourage rooting from the food plants.
I'm trialing 3' of 3/4" nylon rope inside a pool noodle,as a wick, to guarantee water to the plant roots.
Theoretically, its not needed, the roots will grow after the water if/when the level goes down.
So, I'm probably negating the one thing that is Kratky proper about this, and making wicking containers with huge reservoirs and small amounts of soil.
Oh well, I can't help experimenting, at least until I NEED to make progress.
A lot of what motivates me is pursuing lowered cost/reproducibility.
I have gotten my home made bread down to less than 0.50$ a loaf, with great quality and ease of production, through this madness,plus it's fun!
I might try a bottomless bucket, lined with one leg of a pantry hose, and filled with wicking soil, as well.
I wish my biochar production was on point, I would love to try it as my wicking medium.
I will grow some legumes in the barrels as well, perhaps in a tube/sock(?) in the second bung, to see if it shares nitrogen with the other plants.
I can imagine a perennial legume feeding annual salad greens this way.
If my barrels were white, I could imagine Azolla in the reservoirs.
Maybe a barrel of Azolla, for nitrogen production, would do instead.
I've often thought Azolla in a cut down IBC tote would make for a nice green roof for a stationary chicken coop.
Azolla in a thermal solar system is another weird dream...
We needn't bother with circulating pumps, Kratky hydroponics doesn't call for them.
Kratky reservoirs can be kept at the same level or allowed to lower, but must not rise above the initial level lest the roots drown.
We could reserve one barrel for adding water, and chain the rest to that one.
I have found half inch barb fittings plus garden hose make for a very cheap leak proof connection.
Add hot water to that barrel, heated by wood stove, PV solar or thermal solar, etc.
Maybe boil water on a rocket stove, run a condensing coil through the barrel of water.
Add the condensate to the sump barrel.
Most all of the heat captured, and yet tempered.
I'm looking for a propane powered clothes dryer , with the idea that I could smoosh two turds with one bone, but that is really out there.
Maybe build an insulating stem wall, along the front of the green house, and mount a water coil heater there.
Keeping the glazing to a minimum and capturing the heat with a loop that can be a one way thermal trap, seems like a good plan.
On the other hand, keeping things as temporary as possible might be better.
Double layers green house plastic, with another layer of plastic over each barrel, could really push the seasons, cheaply.
Turn the whole thing into a shade house to continue lettuce production into the warmer months.
Wrap the barrels in white to keep the reservoir of water cool.
If I can source them cheaply enough, my new back solar back "porch" might consist of Kratky barrels.
My other solar back "porch" is two cut down IBC totes, made over into wicking containers.
I have a willow growing out of one, I'm not sure what to grow in the other, hardy kiwi maybe?
Add a tent, with clear sides and you have a nearly attached greenhouse, but there are no local building regulations on tents (under 400 square feet) or on planters of any size.
Since I'm aiming for convenience and the thermal benefits of being adjacent, not connected,I don't want the green house(s) to be "attached" anyway.
Shielding an entire solid brick exterior wall from winter air, and summer sun, will be marvelous, if I can pull it off.
Since they Kratky barrels only need a relatively small hole for the plants to access the water, most of the surface is still available to walk on and adsorb solar energy.
If I find using nylon wicks inside of hoses delivers enough water, the holes can be smaller still.
The 'porch" is beneath where my second floor laundry and my bathroom are.
If I'm confident the solar 'porch" won't freeze,running the grey water through a Solvia style vermicomposting filter, and into the "porch" barrels could be great, for (minimally?) heating the "porch".
The overflow water could go right into the downspout drain to the sewer in the winter, and onto the grapes/blackberries during the summer.