Just as a farmer must choose which hydroponic system he will use in his hydroponic garden, he must also choose which medium will be used in their hydroponic gardening systems. Different media are appropriate for different growing techniques. Additionally, different media have different costs, maintenance and results. The combination of hydroponic system and the medium used in that system is what can differentiate one farmer from another and his crops from other hydroponic crops that are available. There are many more media of hydroponic gardens than there are hydroponic systems. Therefore, there is a number of different combinations that can be used in various systems and desirable results can still be reached. Here is a list and descriptions of the different media options that exist for hydroponic gardens:
· Diahydro – Diahydro is a natural sedimentary rock that is extremely high in Silica (87-94%). Silica is an essential component for the growth of plants and the strengthening of a plant’s cell walls.
· Expanded clay – These are baked clay pellets that are best used in hydroponic systems that have carefully controlled water and nutrient solutions. Having a nutrient solution already in the system is needed because the clay pellets have no nutritional value. The clay pellets are baked at a high temperature so that the clay expands and the pellets become porous. The clay pellets can be cleaned and re-used so long as no root systems have found their way into the medium.
· Coir – Coir, or coco peat as it is also called, is made from the outermost shell of the coconut and is 100% natural.
· Rock wool – Rock wool is the most popular hydroponic medium as it can be used in drainage systems that re-circulate as well as drainage systems that do not re-circulate.
· Perlite – Perlite pebbles are made out of volcanic rock that has been heated into a light weight expanded glass. Perlite can be used in both hydroponic and traditional gardening systems. When compared to similar media, Perlite is generally able to hold more air and less water when immersed into the water. The Perlite pebbles are often packed in sleeves as they will float in certain feeding systems.
· Vermiculite – vermiculite is also heated into a light weight pebble. Vermiculite holds more water than Perlite and has a natural “wicking” property. This wicking property proves useful in passive hydroponic systems.
· Sand – Sand is a popular media of hydroponic gardens because it is easy to find and inexpensive to buy. Disadvantages to using sand include its weight, that it does not drain well and that it must be sterilized before it is used again.
· Gravel – Gravel is also inexpensive with the advantage that it is easy to keep clean and drains well. Similar disadvantages include that it is also heavy and needs to be incorporated into a hydroponic system that provides a continuous supply of water to the plants.
· Brick shards – Brick shards are similar in many ways to gravel. Disadvantages to using brick shards include that there is the possibly of them altering the pH of the solution and that as a result they may require extra cleaning before they are used again.
· Polystyrene packing peanuts – Polystyrene packing peanuts are inexpensive, readily available, and have excellent drainage. It is important that only polystyrene packing peanuts be used as other biodegradable packing peanuts can either decompose or clog the system workings or be absorbed by the root system of the plants and pose a health risk to consumers. So long as polystyrene peanuts are used, they can be excellent in a closed tube system (their light weight makes them difficult to work with in any other system).