Hydroponics 101: Methods & Concepts

I have always been fascinated with hydroponics; from when it was something you saw primarily in science fiction and space exploration research, up until you could buy pre-made kits for your tabletop or backyard off the internet. And even now, when I have a bit of yard to grow fruits and vegetables, I’m still tempted by the process.  There are numerous DIY plans out there, with a staggering number of approaches and methods, but they mostly fall into a few broad categories.  Here are simplified explanations of each.

Active vs Passive Hydroponics

Active hydroponic systems employ a pump, to circulate nutrients in a water solution to the roots of your plants and then back to a reservoir where they can be enriched or held for later. These pumps often run on a timer optimized to make sure an optimized balance of fresh nutrients and oxygen reach the roots. They tend to be more expensive than passive systems and require power to run.

Passive hydroponics generally employ some physical method such as wicking to draw nutrient filled water solutions into contact with the root and root medium.  Passive setups tend to be less expensive and easy to build for users getting started.  On the downside, without careful monitoring, it is easy to under or over “water” plants.

Flood & Drain (Ebb & Flow)

Essentially the same thing, these are ways to implement an Active Hydroponic system.  The medium and roots in the system are flooded multiple times per day, providing fresh nutrients and water.  The solution is then drained back to a reservoir where nutrients and oxygen can be reintroduced for the next cycle.  Depending on the root medium and plant types, some fine tuning may be required.


Technically not aquaponics, aeroponics shares enough properties and enthusiasts that a brief overview is probably warranted. The distinction with aeroponics is that the plant's roots are suspended in air, typically in a closed or protected environment. Within, the roots are regularly misted with a fine spray of nutrient-infused water. Aeroponics enjoys the benefits of maximum airflow around roots, high protection from pests & diseases and lower water usage.  However, it is probably the most demanding in terms of structure, support and service.

Deep Water Cultures (DWT)

This technique was developed to support larger plants, and each plant has its own larger bucket into which its roots extend. It uses the most water and nutrients of all the systems, and the solution must be kept oxygenated since it isn’t typically drained, exposing roots to an air cycle.  On the plus side, larger varieties of plants and those with longer vegetative states can be grown.

Nutrient Film Technique (NFT)

This technique employs a constant flow of nutrient water to the plant roots in a shallow bed. As with all Active systems, NFT does requires pumps and powers, and uses more of the later than most Flood & Drain setups. The advantage is the ability to provide a constant supply of nutrient and oxygen rich water and less need to finesse schedules.


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