There are a wide variety of different hydroponic systems. Each has its own characteristics, advantages and disadvantages. In general, I have chosen systems that provide a high density level (plants per square foot) since I don’t have a large yard. Check out these different systems.
NFT System (Nutrient Film Technique)
This is a system that I purchased from American Hydroponics. NFT systems are fairly simple – a shallow flow of nutrient solution passes through the bottom a channel so it is in contact with roots of the plant. A small electric pump moves the water from a reservoir to small 1/4″ tubes that are attached to each channel. At the end of the channels, the water is collected and goes back into the resevoir. One downside to this system is that when the water stops flowing (in a power outage), the plants wilt very quickly.
I liked this system so much that I installed a second system that is outside on my driveway. I found that different varieties of lettuce grow better outdoors than in the greenhouse. Notice the dark red greens in the outdoor system.
A-Frame System (Home made)
This 75 plant unit measure about 5 x 5 and was created for Maker Faire 2016 in San Mateo. When the system is in full production in the summer, you can harvest 2 heads of lettuce per day! It was inspired by this YouTube video (https://youtu.be/EJjAWF2DfWY), but I made some modifications to make it a bit easier to build and smaller in size. It can be built for about $200 in parts over a weekend. Most of these parts can be bought at your local hardware store, although some are probably easier/cheaper to source online.
Vertical Tower System
This vertical system allows you to have a very high density of plants in a very small space. Each tower can hold 32 to 48 plants! Technically, this is an aeroponic system since the roots sit in air and the water drips down the tower to touch each plant. I purchased this system overseas from a company I found on Alibaba. It is similar in design to the Tower Garden, but much less expensive. The bad part is that Alibaba is really not set up to sell to consumers in the US. And the quality of these products is so-so. I stopped using these towers because I experienced leaks along the seams that resulted in lots of algae growth on the outside of the towers.
ZipGrow Tower System
This is a different type of vertical system. ZipGrow towers come from Bright Agrotech. In these systems the plants are in mesh-like polyester material, similar to filter media, that lets air and water contact the roots. The density of plants is much lower than my other vertical system, but plants do grow well in the ZipGrow towers – especially basil. One downside is that towers cost about $65 each (plus shipping).
AutoPots are a completely different type of system. For larger plants with a deeper root system, the other hydroponic systems are not appropriate. I use AutoPots for tomatoes, peppers, cucumbers and more. The plants grow in a soil-like material – I use a mixture of coco (coconut husks) and Perlite. This substrate does not provide any nutrition to the plants. All of the nutrition comes from the enriched water.
Each AutoPot contains a small float valve to control the level of water in each plant tray. The water with nutrients is held in a large tank. As each plant uses more water, it draws water from the tray using a capillary effect. When enough water is consumed, the float valve opens fills the tray.
The great part of the AutoPot system is that the plants are watered/fed automatically. And no power is required. You just need to fill up the tank with water and nutrients every week or so. I’ve had great luck with the system growing lots of tomatoes, peppers and cucumbers.