Texas-based consumer health advocate Mike Adams of non-profit organization Food Rising has developed a new soil-free, non-electric, home-based food grow system called the Mini-Farm Grow Box. The system doesn't require home gardeners to weed out invaders, there are no pumps, motors or complex parts to service and maintain, and it's reported to require about 1/20th of the water of conventional agriculture and about half the space of soil gardening.
The Mini-Farm Grow Box is based on the principles of something called constant bottom feeding non-circulation hydroponics that's been taught by University of Hawaii Professor Bernard Kratky for a number of years. Such a system needs an automatic self-watering float valve to operate correctly. Adams came up with a float design that incorporates 3D-printed components and common household items such as a pencil eraser, a paper clip, a garden hose washer and an old pill bottle. The purpose of the float is to maintain a constant water level in the grow box without the need for circulation or air pumps.
Farmers plant seeds directly into the grow material contained in pots suspended from the removable lid of High Density Polyethylene bins. When sprouting new plants, the grow box is filled with water. A separate bucket uses gravity to feed water through the float valve and into the grow box. Water is cut off automatically when the valve's pencil eraser covers the hole at the bottom of the Float Valve Receiver in the box.
Then it's just a case of topping up the reservoir bucket and waiting for harvest. The system is said to work anywhere with access to sunlight, though can also be used with grow light systems. Food crops can also be grown at waist height, so home gardeners don't need to worry about nagging pains in the lower back.
Food Rising has created a couple of videos to walk makers through the home build process and the print files needed to produce the necessary 3D-printable parts using a t-glase filament-compatible printer are freely available for download at Food Rising's website, though pre-build systems are also being offered for sale. The non-profit is also raising funds to donate systems to 250 schools across the United States.
Source: Food Rising
A good non-circulating hydroponic system does not need a custom-made float valve. If a float valve is deemed critical to such a system (which it is absolutely NOT) then why not buy a cheap one off-the-shelf instead of screwing around with scavenging a bunch of parts then finding someone with a 3-D printer (or God forbid, buying one at huge expense) to manufacture the "missing float valve parts" that cannot be scavenged? Seems like this guy is more interested in promoting 3-D printing of unnecessary parts and furthering his own political agenda than he is in helping people create their own AFFORDABLE non-circulating hydroponic systems!
A float valve is an expensive, potentially problematic, and absolutely unnecessary way to regulate the water level compared with a much simpler and far more common inverted water bottle or inverted water tank. Who wants to waste their time constructing a specially made float valve, which is clearly subject to malfunction and failure, when a homemade $4 chicken waterer made out of a 5-gallon bucket and a pan (Google: 4 Dollar Chicken Feeder & Water) will work far more reliably and cost far less?!
And, so much for this being 'open source' - the 'how to' videos require registration - which is deeply against open source principles.