There are two main types of Hydroponics, solution culture and medium culture, both of which have their own sub-types, depending on the method being used.  Solution culture hydroponices has two sub-types, static solution and continuous flow solution.  Static solution hydroponics involves growing plants in containers of solution that has the right nutrient balance, the size of the container can vary from a bucket to a tank, depending on the amount of plants you wish to grow. If the containers being used are clear then it will be necessary to cover them with a bin-liner or something similar to prevent the light getting in as this will promote the growth of algae in the containers. Generally the solution will be aerated, however if this is noty possible then it is necessary to keep the solution level low enough to allow some of the roots of the plants to be exposed in order to get oxygen.  Aeration can be provided using something as simple as an aquarium pump and tubing to provide oxygen to the solution.  The nutrient solution will need to be changed on a regular basis, either to a timetable or when the nutrient levels drop below a certain point to ensure the plants are receiving optimum nutrient levels.

Continuous flow solution hydroponics eliminates the need for changing the nutrient solution on a regular basis as this can be controlled in a central tank easily.  The nutrient solution is pumped through the containers giving the plants a continuous flow of nutrient solution.  A slight variation on the continuous flow method is the nutrient film technique, often referred to as “NFT”.  This involves growing the plants in containers that have a channel of water so shallow it is hardly more than a film of nutrient solution running over the roots of the plants, hence the name nutrient film technique.  This allows a thick root mat to develop which is moist and exposed to air meaning the plants not only have optimum nutrient levels but also optimum oxygen levels giving excellent yields of very high quality plants.

Medium culture hydroponics involves the use of a substance for the roots to bed into.  There are various different mediums available, some with nutrients, others without. Diahydro is a sedimentary rock that is made from the fossilized remains of diatoms.  Diahydro is incredibly high in Silica which is essential for the strengthening of cell walls and for plant growth.  Expanded clay is a medium suitable for all hydroponic systems, consisting of pellets of baked clay which are washable and re-useable making it an economical medium however it has no nutrient value. Rock wool is one of the most commonly used mediums in hydroponics, an insert substrate, it lends itself perfectly for use in drainage and circulation systems.

Other, more cheaply available mediums such as sand and gravel are also viable options, although sand is of course heavy and doesn’t drain particularly well. Small gravel (such as aquarium or rockery gravel) drains well and is easy to clean.