DIY float valve for passive hydroponics takes advantage of 3D printing

[Billy] has a particular interest in passive hydroponics (also known as the Kratky method), which is a way of growing plants in nutrient-rich water that does not circulate. As the plant grows and the liquid level drops, only the root tips remain submerged while more and more of the root surface is exposed to oxygen in a harmonious balance. However, “thirsty” types of plants (tomatoes, for example) upset this balance and the system must be changed. To remedy this, [Billy] designed and printed a passive float valve system which takes care of filling the tank only when needed, without using pumps or any other electrical equipment.

Commercial or industrial float valves are too large for use in its small tanks, which has led [Billy] to test dozens of DIY designs. He used everything from plastic water bottles to pipe ends, but nothing quite measured. With 3D printing, [Billy] was able to create a tight, lightweight float that matched the housing and tube locations exactly.

A silicone strip works as a sealant.

The path [Billy]The float valve works by using a hollow object as a kind of floating plug inside a housing. When the water level is high, the floating object lifts and presses a silicone strip against an outlet, preventing water from flowing out. If the water level is low, the floating plug falls off and the water can flow freely. With a reservoir of fresh, nutrient-rich water placed above the grow tank, gravity takes care of pushing fresh food through a tube, so no active pumps are needed. Combined with a passive float valve, the system pretty much works on its own.

look [Billy] take a tour of its system and valve design in the video embedded below. He has a lot of experience when it comes to working with projects involving liquids. Only someone as comfortable as him would make his own dishwasher.