Hydroponic drip systems that use a pump to move nutrients are known as active systems. Drip hydroponics usually use a growing media, such as vermiculite or perlite, to both support the plant and to hold moisture and nutrients on the roots. This type of hydroponic system is the most commonly used. Drip systems can be made inexpensively or purchased. The biggest attractions of a drip system are its flexibility and low cost.
The Basic System
This active hydroponic system uses a pump in a reservoir to move a nutrient mixture up through drip line to a growing tray. Emitters run from the drip line to each plant. An air stone in the reservoir adds oxygen to the nutrient mixture. The system relies on the nutrient liquid to feed the plant roots and provide them with oxygen. The plants in the growing tray are supported by a sterile growing media.
Recovery and Non-Recovery Systems
Simply Hydroponics and Organics says active drip system hydroponics can also be recovery or non-recovery systems. In a recovery system, the excess nutrient feed runs back into the reservoir to be reused. The non-recovery system does not collect the excess nutrient feed. The recovery system has less waste, but does require continual testing for pH and nutrient concentration. The non-recovery system may not need the same amount of testing, but it does require that watering cycles are closely monitored to reduce nutrient waste and runoff.
Timers and Growing Media
Timers are used to ensure that the correct amount of nutrient feed liquid runs to the plants. The plants need time for the solution to drain so they can take in oxygen. The Growing Edge says that as the nutrients drain, they also wash out salts that have built up in the growing media. Several forms of media can be used. Rockwool, perlite and vermiculite are the most common. However, coconut fiber works, and there are commercial media mixtures that can be purchased. The only requirement is that the media be soil free and sterile.
A Flexible System
Drip systems are flexible, because the nutrient flow can be adjusted for individual plants within the same system by changing the number of emitters or their size, allowing plants with different nutrient and water requirements to be grown together. Although drip systems are easy to set up, construct and operate, maintenance can be a problem, especially if you use organics in your nutrient solution. The emitters clog on occasion and need thorough cleaning.
Drip systems don't allow for plants to be moved around, so it is necessary to place plants that have similar nutritional needs and size. Drip systems don't work well with large plants or plants that require long growing times. Annual herbs and flowers do well. Lettuce and other salad greens do well in drip systems. The Growing Edge recommends germinating plants from seed rockwool starter cubes, then placing the starter cubes in the drip system.