What is a Passive System?
Passive systems use a capillary or wick system to deliver nutrients directly to a plant’s roots. This means that nutrients are absorbed by the growing medium or a wick and passed to the plant’s roots. Passive systems are incredibly simple; they don’t even require electricity to function. They do. however, require you to change the water more frequently than any other hydroponic system. Since there is no pump, there’s nothing to stop algae from growing and soiling the water quality. Passive systems also aren’t as efficient at recovering nutrients, as there is no way to recover what isn’t directly absorbed by the plants. These systems work, but aren’t viewed as the best option for those looking to grow hydroponically.
What is an Active System?
Active systems are more complicated than passive systems, although the degree of difficulty depends on the system you want to use. Active systems rely on pumps or other devices to actively move the solution from a reservoir to the roots. This allows for far better growing environments and nutrient efficiency. Most active systems allow nutrient solution not absorbed by the plant to drip back into the reservoir it came from. Since you can control when the nutrient solution is being brought to the plant’s roots, you can also ensure they get enough oxygen for proper growth. Here are a few popular examples of active systems:
Ebb and Flow systems, commonly referred to as Flood and Drain systems, are more advanced than passive systems but are still very easy to use. They require pumps that raise and lower the water level to feed your plants. The pump turns on and off based on a timer you set and works automatically. In these systems, a reservoir sits under the plants you wish to grow. The pumps the raise the water to feed the plants and shut down when the water needs to lower. This allows the plant to get the oxygen it needs to survive.
Drip systems are perfect for irrigating multiple crops. A large reservoir sits under several containers containing different plants. A mainline runs across the middle of the reservoir carrying the nutrient dense mixture. Mini-tubes stem out from the mainline and lead into the containers with the plant you want to grow. The nutrient dense mixture then drips into each crop individually, allowing for mass irrigation! These systems also allow you to manage the flow rate of the drip, so you can tailor your growing method for each plant.
Areo-hydroponics is a term that encompasses a few sub-categories, but all aero-hydroponic systems are based on using the air to move water. These are extremely eco-friendly systems, and they are a great option for small scale operations. Here are some aero-hydroponic systems:
Air Pumps – Used for small-size systems. A “y” shaped tube goes into a container with nutrient dense material sitting under the plant and growing media. Air flows into the tube, causing the water to bubble and rise up the other side of the tube. The water then disperses evenly across the growing media, thanks to a ring-shaped spigot.
Water Pumps – Water pumps are used for larger scaled operations. These actually look quite a bit like drip systems. Two rows of plants, placed in a hollowed out white PVC tube, sit over a container holding the nutrient dense material. There are spigots that branch out from a center mainline, but instead of dripping they plunge into the PVC and spray powerfully. This oxygenates the plants and moves the nutrient solution throughout the container.
Vortex – Used for smaller systems, the vortex method is one of the most efficient options out there. The plants sit on the top of an inverted cone, with nutrient solution resting beneath them inside the cone. The 12V motor kicks on and spins the water, creating a vortex that splashes the plants from below. The only problem with this method is that plants can’t be too big. If the roots are too long, they’ll get tangled and shredded by the spinner.
Deep Water Cultivation
Deep Water Cultivation is a variation on the oldest methods of growing plants hydroponically. In these systems, a basin filled with nutrient solution is covered with a styrofoam sheet with a hole in the middle where the plant sits. At the bottom of the solution, place an air stone or air curtain connected to a small pump to power it. Then, sit back and let the plant grow! It’s that simple.
NFT systems, or Nutrient Film Technique systems, are another advanced system meant for expert gardeners. Once your seedlings or cutting has developed a strong root system, you’ll place it in a gully. The plant’s roots will hang down onto capillary matting that rests at the bottom of the gully. Aerated nutrient solution constantly flows from one end of the gully to the other, gently covering the roots. These systems offer arguably the best growth of any hydroponics set-up. But they are extremely fragile because there is no growing medium. Roots must constantly be bathed in the solution, so if your pump shuts down or the gully clogs you’ll have to act quickly to make sure your plants aren’t damaged.