Growing Mediums
In order to serve as a suitable replacement for soil, the substrate must be capable of supporting the root system, accumulating moisture and nutrients. It should be inert, free of insects and diseases, and durable.
Moreover, the substrate should permit adequate aeration of the roots, and have first-rate drainage ability. Plants roots need sufficient access to oxygen from the air, in order to grow and take up water and nutrients. Poor drainage can lead to decreased growth, stunting, wilting, and discoloration of the leaves- in the worst cases “drowning the plant.”
There are several different types of growing mediums used in hydroponic gardening, none of which are soil. These mediums are considered to be inert because alone they have no nutritional value. As a substitute, a nutrient solution is supplied to them by some means. The most popular mediums for hydroponics are Rockwool, Gro-rox, Vermiculite, Perlite, and Coconut fiber. Sand and gravel are also used but must be thoroughly cleaned before use, which is a problem in its self. Each of these substances differs in size, volume, and color. But all of them are highly suitable for hydroponics.
Rockwool
This is probably the most commonly used medium in hydro systems. It is available in a variety of sizes. There are starter cubes that are used to germinate seeds, and can be used for cloning. Additionally, larger cubes are available that are used throughout every stage of plant growth. Rockwool absorbs up to forty times its weight of water, which keeps the roots very moist long after saturation. The only downside of using Rockwool is that it has a tendency to collect toxic mineral deposits, from the solution. So it becomes mandatory to flush out the cubes every few days with fresh water. The advantage to using Rockwool is that it is inexpensive and readily attainable.
Perlite
Perlite is not a brand name but a generic term for naturally occurring siliceous rock. The distinguishing feature, which sets Perlite apart from other volcanic glasses, is that when heated to a point it expands from four to twenty times its original volume. This expansion is due to the presence of water, in the rock. When briskly heated to above 1600 degrees F (871 degrees C), the crude rock pops in a manner similar to popcorn. As the water vaporizes it creates tiny pores. These pores give the rock its amazing lightweight, and its ability to absorb water. This expansion process also creates one of Perlites’ most distinguishing characteristics, its white color. While the crude rock may range from transparent to light gray, to a glossy black-the color of expanded Perlite looks snowy white, or grayish-white. Expanded Perlite can be manufactured to weigh as little as 2 pounds per cubic foot, which allows it to take up a great deal of space but at the same time weigh very little. Since Perlite is a form of natural glass and has a pH of approximately 7, it is classified as chemically inert. This medium is used in just about every system available on the market.
Vermiculite
Vermiculite is a natural rock, like Perlite, so it will not deteriorate, but it differs in composition. It is composed of silicates, and looks like crushed mica. It has fine aeration properties, but is not always neutral in pH. It tends to be alkaline (basic), and can be as high as 9.5 depending on where it was mined, so be sure to test it and adjust your nutrients accordingly. Vermiculite is very absorbent and can hold many times its weight in water. It must be used in containers because of its size. It is usually used in wick systems to help draw the solution upward.
Coconut Fiber
Coconut Fiber is an entirely natural medium that can be used in hydroponic systems. It is composed of organic compounds, which make it biodegradable- this can be messy. This medium holds water very well and can retain small amounts of nutrients. It is possible to reuse coconut fiber for two or three cycles, but we strongly recommend using a fresh batch each time you grow to prevent algae and diseases. A disadvantage to using the fiber is that particles from the fiber fall and saturate the solution, which in turn can clog pumps or tubes.
Fired Clay Pebbles
This is one of the more popular mediums for hydroponic cultivation. These clay pebbles are inexpensive; they are pH balanced, and can be reused numerous times. They are made by heating treated clay pebbles rapidly, which causes them to expand. They are porous and hold water. However, the clay pebbles do not retain the water well, so it would be best to use them in conjunction with coconut fiber, Rockwool, or Vermiculite. Begin your seeds or clones in another medium and then place them in the clay pebbles. The best clay pebbles are the ones that are irregular in shape, with many pores. Avoid the perfectly smooth ones because they will not hold the roots, or water, well.
One of the most obvious decisions hydroponicists have to make is which medium they should use. Different media are appropriate for different growing techniques.
Diahydro
Diahydro is a natural sedimentary rock medium that consists of the fossilized remains of diatoms. Diahydro is extremely high in Silica (87-94%), an essential component for the growth of plants and strengthening of cell walls.
Expanded clay
Hydroton brand expanded clay pebbles.
Also known under the trademarks ‘Hydroton’ or LECA (light expanded clay aggregate), these small, round baked spheres of clay are inert and are suitable for hydroponic systems in which all nutrients are carefully controlled in water solution. The clay pellet is also inert, pH neutral and do not contain any nutrient value.
The clay is formed into round pellets and fired in rotary kilns at 1200°C. This causes the clay to expand, like popcorn, and become porous. It is light in weight, and does not compact over time. Shape of individual pellet can be irregular or uniform depending on brand and manufacturing process. The manufacturers consider expanded clay to be an ecologically sustainable and re-usable growing medium because of its ability to be cleaned and sterilized, typically by washing in solutions of white vinegar, chlorine bleach or hydrogen peroxide (H2O2), and rinsing completely.
Another viewpoint is clay pebbles are best not re-used even when they are cleaned due to root growth which may enter the medium. Breaking open a clay pebble after a crop has been grown will reveal this. However, this view is generally not widely shared.
Rockwool
Rockwool is probably the most widely used medium in hydroponics. Made from basalt rock it is heat-treated at high temperatures then spun back together like candy floss. It comes in lots of different forms including cubes, blocks, slabs and granulated or flock.
Rockwool is an excellent inert substrate for both ‘free drainage’ and recirculating systems. In free drainage or run-to-waste systems, the chance of disease spread is greatly lessened. Rockwool is also lightweight and self-contained, which allows plants to be grown at different densities in different stages - young plants can be grown to an advanced stage in a small area before being planted out into the main growing area, thus improving crop turnaround. Its light weight also permits setting up to be quick and inexpensive. Because it is light and rigid it eliminates back-breaking work in preparation and planting and gives substantial labor-saving costs. Rockwool is noted for providing a favourable root environment, thus minimizing plant stress. Root temperature can also be controlled, thus giving substantial energy savings. Rockwool initially causes an increase in pH level. You must adjust the pH level of the nutrient solution to counteract this. A pH level of 5.5-6.5 should suffice to create a suitable pH.
The disadvantages of rockwool are few. Although relatively inexpensive, because of its bulk, transport costs to remote regions can be prohibitive. However, the fact that it can be used several times over will reduce the growers overall costs. Before handling, gloves and long shirt sleeves should be worn to prevent minor skin irritation. This can also be lessened by wetting the rockwool before handling. When this medium is dry, care needs to be taken so as not to inhale any particles; inhaling such particles may carry a health risk.
Coir
Coco peat, also known as coir or coco, is the leftover material after the fibres have been removed from the outermost shell (bolster) of the coconut. It took 10 centuries to make this waste a viable plant substrate. The first description of the coco process dates from the 11th century and was recorded by Arabian traders. In 1290, Marco Polo described the process of extracting fibres from coconuts. For centuries, this process remained unchanged. Coco peat was a waste product from factories that used coco fibre as a raw material for making sailing ropes, chair seats and mattress fillings.
Coco is a 100% natural grow and flowering medium, which has proven its value across years and years. Coco is not only a high quality product, but also an environmentally friendly product[The Hydroponic Bible]. For many years the raw material was considered waste material, and enormous useless “Coco Mountains” appeared in the landscapes of countries like Sri Lanka and India. By developing a special biological composting process this “waste” transformed into a high quality product. This innovation was, and still is, an important contributor to the local economy of India and Sri Lanka. This and the unique growth characteristics ensure coco is the medium of the moment and the future.
The coco substrate is an environmentally friendly product. No energy wasteful production methods are used during the production of this long-lasting cultivation medium. Coconut fibres are obtained from the coconuts’ husks which are a natural product that can be harvested throughout the year. Coir comes in bags and in slabs.
Some types of coir are very high in sodium (salt) due to the nature of coconut palms growing on island environments and being processed in the salt air. Quality coir has not been sterilized or heat treated and so retains its natural sponge-like qualities as well as the natural, beneficial trichoderma fungi which has been scientifically shown to combat root rot and other diseases.[The Hydroponic Bible] Trichoderma is also well-known for promoting root growth.[citation needed]
This substrate combines the tolerant, organic nature of soil with the precision of rockwool. Due to the special characteristics of the substrate the nutrient doesn’t have a grow and flower variant, there is just one unique formulation for both growth and blooming phase. Due to the unique buffering capability of the coir substrate, and its sponge-like structure, the nutrients needed to ensure high yields are stored in the coco. This means that the plant itself can regulate the amount and timing of its nutrient intake.
Coconut fibres have sufficient capillary action to retain enough water and nutrients. This means that the plant can go for longer periods with-out water, which could happen if a feeding pump was to break down for example.
Quality coir can be used a number of times and makes an excellent soil improver after use.
Perlite
Perlite is a volcanic rock that has been superheated into very lightweight expanded glass pebbles. It is used loose or in plastic sleeves immersed in the water. It is also used in potting soil mixes to decrease soil density. Perlite has similar properties and uses to vermiculite but generally holds more air and less water. If not contained, it can float if flood and drain feeding is used.
Vermiculite
Like perlite, vermiculite is another mineral that has been superheated until it has expanded into light pebbles. Vermiculite holds more water than perlite and has a natural “wicking” property that can draw water and nutrients in a passive hydroponic system. If too much water and not enough air surrounds the plants roots, it’s possible to gradually lower the medium’s water-retention capability by mixing in increasing quantities of perlite.
Sand
Sand is cheap and easily available. However, it is heavy, it does not always drain well, and it must be sterilized between use.
Gravel
The same type that is used in aquariums, though any small gravel can be used, provided it is washed first. Indeed, plants growing in a typical traditional gravel filter bed, with water circulated using electric powerhead pumps, are in effect being grown using gravel hydroponics. Gravel is inexpensive, easy to keep clean, drains well and won’t become waterlogged. However, it is also heavy, and if the system doesn’t provide continuous water, the plant roots may dry out.
(Compiled for your growing pleasure)
I take no Credit - copied and Pasted for the greater knowledge of all! - JM
In order to serve as a suitable replacement for soil, the substrate must be capable of supporting the root system, accumulating moisture and nutrients. It should be inert, free of insects and diseases, and durable.
Moreover, the substrate should permit adequate aeration of the roots, and have first-rate drainage ability. Plants roots need sufficient access to oxygen from the air, in order to grow and take up water and nutrients. Poor drainage can lead to decreased growth, stunting, wilting, and discoloration of the leaves- in the worst cases “drowning the plant.”
There are several different types of growing mediums used in hydroponic gardening, none of which are soil. These mediums are considered to be inert because alone they have no nutritional value. As a substitute, a nutrient solution is supplied to them by some means. The most popular mediums for hydroponics are Rockwool, Gro-rox, Vermiculite, Perlite, and Coconut fiber. Sand and gravel are also used but must be thoroughly cleaned before use, which is a problem in its self. Each of these substances differs in size, volume, and color. But all of them are highly suitable for hydroponics.
Rockwool
This is probably the most commonly used medium in hydro systems. It is available in a variety of sizes. There are starter cubes that are used to germinate seeds, and can be used for cloning. Additionally, larger cubes are available that are used throughout every stage of plant growth. Rockwool absorbs up to forty times its weight of water, which keeps the roots very moist long after saturation. The only downside of using Rockwool is that it has a tendency to collect toxic mineral deposits, from the solution. So it becomes mandatory to flush out the cubes every few days with fresh water. The advantage to using Rockwool is that it is inexpensive and readily attainable.
Perlite
Perlite is not a brand name but a generic term for naturally occurring siliceous rock. The distinguishing feature, which sets Perlite apart from other volcanic glasses, is that when heated to a point it expands from four to twenty times its original volume. This expansion is due to the presence of water, in the rock. When briskly heated to above 1600 degrees F (871 degrees C), the crude rock pops in a manner similar to popcorn. As the water vaporizes it creates tiny pores. These pores give the rock its amazing lightweight, and its ability to absorb water. This expansion process also creates one of Perlites’ most distinguishing characteristics, its white color. While the crude rock may range from transparent to light gray, to a glossy black-the color of expanded Perlite looks snowy white, or grayish-white. Expanded Perlite can be manufactured to weigh as little as 2 pounds per cubic foot, which allows it to take up a great deal of space but at the same time weigh very little. Since Perlite is a form of natural glass and has a pH of approximately 7, it is classified as chemically inert. This medium is used in just about every system available on the market.
Vermiculite
Vermiculite is a natural rock, like Perlite, so it will not deteriorate, but it differs in composition. It is composed of silicates, and looks like crushed mica. It has fine aeration properties, but is not always neutral in pH. It tends to be alkaline (basic), and can be as high as 9.5 depending on where it was mined, so be sure to test it and adjust your nutrients accordingly. Vermiculite is very absorbent and can hold many times its weight in water. It must be used in containers because of its size. It is usually used in wick systems to help draw the solution upward.
Coconut Fiber
Coconut Fiber is an entirely natural medium that can be used in hydroponic systems. It is composed of organic compounds, which make it biodegradable- this can be messy. This medium holds water very well and can retain small amounts of nutrients. It is possible to reuse coconut fiber for two or three cycles, but we strongly recommend using a fresh batch each time you grow to prevent algae and diseases. A disadvantage to using the fiber is that particles from the fiber fall and saturate the solution, which in turn can clog pumps or tubes.
Fired Clay Pebbles
This is one of the more popular mediums for hydroponic cultivation. These clay pebbles are inexpensive; they are pH balanced, and can be reused numerous times. They are made by heating treated clay pebbles rapidly, which causes them to expand. They are porous and hold water. However, the clay pebbles do not retain the water well, so it would be best to use them in conjunction with coconut fiber, Rockwool, or Vermiculite. Begin your seeds or clones in another medium and then place them in the clay pebbles. The best clay pebbles are the ones that are irregular in shape, with many pores. Avoid the perfectly smooth ones because they will not hold the roots, or water, well.
One of the most obvious decisions hydroponicists have to make is which medium they should use. Different media are appropriate for different growing techniques.
Diahydro
Diahydro is a natural sedimentary rock medium that consists of the fossilized remains of diatoms. Diahydro is extremely high in Silica (87-94%), an essential component for the growth of plants and strengthening of cell walls.
Expanded clay
Hydroton brand expanded clay pebbles.
Also known under the trademarks ‘Hydroton’ or LECA (light expanded clay aggregate), these small, round baked spheres of clay are inert and are suitable for hydroponic systems in which all nutrients are carefully controlled in water solution. The clay pellet is also inert, pH neutral and do not contain any nutrient value.
The clay is formed into round pellets and fired in rotary kilns at 1200°C. This causes the clay to expand, like popcorn, and become porous. It is light in weight, and does not compact over time. Shape of individual pellet can be irregular or uniform depending on brand and manufacturing process. The manufacturers consider expanded clay to be an ecologically sustainable and re-usable growing medium because of its ability to be cleaned and sterilized, typically by washing in solutions of white vinegar, chlorine bleach or hydrogen peroxide (H2O2), and rinsing completely.
Another viewpoint is clay pebbles are best not re-used even when they are cleaned due to root growth which may enter the medium. Breaking open a clay pebble after a crop has been grown will reveal this. However, this view is generally not widely shared.
Rockwool
Rockwool is probably the most widely used medium in hydroponics. Made from basalt rock it is heat-treated at high temperatures then spun back together like candy floss. It comes in lots of different forms including cubes, blocks, slabs and granulated or flock.
Rockwool is an excellent inert substrate for both ‘free drainage’ and recirculating systems. In free drainage or run-to-waste systems, the chance of disease spread is greatly lessened. Rockwool is also lightweight and self-contained, which allows plants to be grown at different densities in different stages - young plants can be grown to an advanced stage in a small area before being planted out into the main growing area, thus improving crop turnaround. Its light weight also permits setting up to be quick and inexpensive. Because it is light and rigid it eliminates back-breaking work in preparation and planting and gives substantial labor-saving costs. Rockwool is noted for providing a favourable root environment, thus minimizing plant stress. Root temperature can also be controlled, thus giving substantial energy savings. Rockwool initially causes an increase in pH level. You must adjust the pH level of the nutrient solution to counteract this. A pH level of 5.5-6.5 should suffice to create a suitable pH.
The disadvantages of rockwool are few. Although relatively inexpensive, because of its bulk, transport costs to remote regions can be prohibitive. However, the fact that it can be used several times over will reduce the growers overall costs. Before handling, gloves and long shirt sleeves should be worn to prevent minor skin irritation. This can also be lessened by wetting the rockwool before handling. When this medium is dry, care needs to be taken so as not to inhale any particles; inhaling such particles may carry a health risk.
Coir
Coco peat, also known as coir or coco, is the leftover material after the fibres have been removed from the outermost shell (bolster) of the coconut. It took 10 centuries to make this waste a viable plant substrate. The first description of the coco process dates from the 11th century and was recorded by Arabian traders. In 1290, Marco Polo described the process of extracting fibres from coconuts. For centuries, this process remained unchanged. Coco peat was a waste product from factories that used coco fibre as a raw material for making sailing ropes, chair seats and mattress fillings.
Coco is a 100% natural grow and flowering medium, which has proven its value across years and years. Coco is not only a high quality product, but also an environmentally friendly product[The Hydroponic Bible]. For many years the raw material was considered waste material, and enormous useless “Coco Mountains” appeared in the landscapes of countries like Sri Lanka and India. By developing a special biological composting process this “waste” transformed into a high quality product. This innovation was, and still is, an important contributor to the local economy of India and Sri Lanka. This and the unique growth characteristics ensure coco is the medium of the moment and the future.
The coco substrate is an environmentally friendly product. No energy wasteful production methods are used during the production of this long-lasting cultivation medium. Coconut fibres are obtained from the coconuts’ husks which are a natural product that can be harvested throughout the year. Coir comes in bags and in slabs.
Some types of coir are very high in sodium (salt) due to the nature of coconut palms growing on island environments and being processed in the salt air. Quality coir has not been sterilized or heat treated and so retains its natural sponge-like qualities as well as the natural, beneficial trichoderma fungi which has been scientifically shown to combat root rot and other diseases.[The Hydroponic Bible] Trichoderma is also well-known for promoting root growth.[citation needed]
This substrate combines the tolerant, organic nature of soil with the precision of rockwool. Due to the special characteristics of the substrate the nutrient doesn’t have a grow and flower variant, there is just one unique formulation for both growth and blooming phase. Due to the unique buffering capability of the coir substrate, and its sponge-like structure, the nutrients needed to ensure high yields are stored in the coco. This means that the plant itself can regulate the amount and timing of its nutrient intake.
Coconut fibres have sufficient capillary action to retain enough water and nutrients. This means that the plant can go for longer periods with-out water, which could happen if a feeding pump was to break down for example.
Quality coir can be used a number of times and makes an excellent soil improver after use.
Perlite
Perlite is a volcanic rock that has been superheated into very lightweight expanded glass pebbles. It is used loose or in plastic sleeves immersed in the water. It is also used in potting soil mixes to decrease soil density. Perlite has similar properties and uses to vermiculite but generally holds more air and less water. If not contained, it can float if flood and drain feeding is used.
Vermiculite
Like perlite, vermiculite is another mineral that has been superheated until it has expanded into light pebbles. Vermiculite holds more water than perlite and has a natural “wicking” property that can draw water and nutrients in a passive hydroponic system. If too much water and not enough air surrounds the plants roots, it’s possible to gradually lower the medium’s water-retention capability by mixing in increasing quantities of perlite.
Sand
Sand is cheap and easily available. However, it is heavy, it does not always drain well, and it must be sterilized between use.
Gravel
The same type that is used in aquariums, though any small gravel can be used, provided it is washed first. Indeed, plants growing in a typical traditional gravel filter bed, with water circulated using electric powerhead pumps, are in effect being grown using gravel hydroponics. Gravel is inexpensive, easy to keep clean, drains well and won’t become waterlogged. However, it is also heavy, and if the system doesn’t provide continuous water, the plant roots may dry out.
(Compiled for your growing pleasure)
I take no Credit - copied and Pasted for the greater knowledge of all! - JM
