Hydroponics implies growing of the plants without soil; however, they still need medium to grow in. Hydroponics stores online or local ones offer a wide range of mediums to choose from, and it is better to know them to make the optimal choice.

Different Types of Growing Mediums

Although almost any substances can more or less serve as the growing medium, the most popular are those named below:

- Water / Air / Sand / Gravel

- Vermiculite / Perlite

- Lava Rock

- Sphagum Moss / Sawdust

- Expanded clay pellets

- Oasis Cubes

- Coconut Fiber

- Fiberglass Insulation

- Proprietary Soilless Mix

- Rockwool

Although rockwool is the last in the list, it can definitely be named the most popular growing medium among hydroponics gardeners, because it is easy and cozy to use.

Rockwool was initially used as insulation material in building. However, hydroponic gardeners in Denmark were the first to discover its advantages when used as a growing medium. Nowadays, rockwool is highly valued and commercially available in the forms of rockwool cubes and rockwool plugs. To produce rockwool stone and sand are melted together and then spun into various shapes and sizes, which sounds similar to the production of cotton candy.

Rockwool Advantages

Rockwool cubes (sized 36” by 12” by 3”) are very convenient to use, because they can be easily cut to a shape matching your needs. This material perfectly holds water and air, being very porous. Therefore, the roots of the plants will be protected both from rotting and drying out in case of the pump malfunction or other event long enough for you to be able to correct the situation.

The granules of the rockwool plugs keep together well and are not less easy to use.

Precautions

Unfortunately, rockwool has weakpoints as well, besides the benefits mentioned above. It can hardly be called environmentally friendly, as it is made of rock and thus does not bio-degrade, requiring some efforts to eliminate it. Moreover, it can be dangerous for the human health, causing silicosis if accidentally inhaled. For this reason, it is recommended to wear a face mask with a HEPA filter and handle rockwool carefully.

One more thing, a gardener should keep in mind while using rockwool, is that this material has a very high pH level, which should be reduced with available acidic substances and regularly checked.

In spite of the rockwool cons, it is still so easy and comfortable to use that it remains the most popular growing medium type among the hydroponics gardeners. The only thing to do is to take necessary precautions while working with it.

Soil less Mixtures

There is a great amount of soil less mixtures available, which contain different ingredients. Sphagnum moss, perlite, and vermiculite are the most widely spread hydroponics components, used in such mixtures.

Being organic, soil less growing media are usually used for container gardening wick systems or on-recovery drip systems. It is also possible to use soil less mixtures in recovery systems, however, it is necessary to remember that because of very fine particles in such mixtures, they can clog tubes, pumps and drip emitters, when used without a good filtration system. By the way, according to the urban gardeners, one can use panty hose as a filter: just fit it to the return line and to the pump inlet, and all the tiny particles will be filtered out.

Most soil less mixes form a good growing medium for multiple hydroponic and organic gardens, because they can hold water well, have great wicking action, and, at the same time, they provide a reasonable amount of air to the roots of growing plants.

Coconut Fiber

The popularity of coconut fiber as growing medium increases rapidly around the world. Being the first totally organic growing medium, providing highest performance for hydroponic systems, coconut fiber may soon become the most popular growing medium ever. It is interesting to note that coconut fiber is, actually, a waste product, which contains the powdered husks of coconuts.

In comparison to rockwool, coconut fiber is characterized with higher oxygen capacity and water retaining. These features are important advantages for hydroponic systems with intermittent watering cycles.

Coconut fiber also contains a lot of root stimulating hormones, thus offering some protection against fungus infestation and other root diseases. The mixture of 50% coconut fiber and 50% expanded clay pellets is considered to be the perfect growing medium.

However, it is necessary to underline one precaution when buying coconut fiber. Avoid purchasing a low grade coconut fiber, which is very fine grained and contains a high level of sea-salts. Such coconut fiber will have negative and disappointing effect on hydroponic system.

The most widely-spread growing medium is, perhaps, rockwool. Originally used for insulation purposes and also known as mineral insulation, rockwool was first used as growing medium by Dane gardeners. Now, it is frequently used for drip-style indoor gardens around the globe.

Rockwool is produced by a process similar to making cotton candy: a particular mixture of sand and rock is melted and then turned into fibers by spinning the mixture to form products of multiple shapes and dimensions, from 1″ starter cubes and up to large slabs of  3″x12″x36″ in size. The variety of available forms and sizes turns rockwool into one of the most widely-used growing mediums.

Key advantages, as well as disadvantages, of this popular growing medium are listed below.

Rockwool’s Strong Points

HOLDING WATeR – rockwool as a growing medium in hydroponics systems is capable of holding a large amount of water. This creates an additional protection for situations, when water is not supplied because of power outages or failures in pumping or other gardening equipment.

ACCUMULATING AIR – up to 18 % of air are constantly kept by rockwool. Due to this capability, there is a very little risk to over water rockwool; besides, the plants are always supplied with enough amount of oxygen.

MULTIPLE SHAPES AND SIZES AVAILABLE – whether it is a small 1″ cube for seeds propagation or a large 3×12x36 inches slab for huge plant, rockwool offers a wide variety of shapes and sizes to choose from. Besides, loose rockwool is also available, designed for filling different plant containers.

NO DUST AND EASY TO USE – since rockwool maintains its form almost perfectly, it cannot be scattered accidentally. Besides, usually packed into plastic rockwool is a very clean material that is easy and comfortable to work with.

Rockwool’s Weak Points

NOT A “GREEN” MATERIAL – rockwool is claimed to be not environment-friendly material, because of its almost indefinite time of breakdown.

HEALTH HAZARDS – rockwool particles and fibers pose serious health danger, especially for human lungs. That is why it is necessary to wear a protective dust mask, while working with rockwoll.

pH PROBLEMS – because of rockwool’s high pH level, it is necessary to balance pH level in the nutrient solution properly and make it suitable for the plants, you are growing. In general, the use of rockwool requires more routine work to keep pH level of your nutrient solution at steady level.

LONG PRE-SOAK PERIOD – before rockwool can be used in the hydroponic system, it should be soaked for at least 24 hours beforehand. Other growing media usually do not require pre-soaking, it is enough just to well-water them.

Along with water, hydroponics plant nutrients, CO2 and oxygen, grow lights is the key basic component, required by plants to live. Providing additional light is necessary for indoor gardening. Furthermore, light should resemble the sunlight as much as possible. The major concern with other types of lights is that they do not produce light in the appropriate spectrum, required by plants.

Being the most efficient bulbs, HPS bulbs are commonly used by gardeners. Producing light in red and yellow spectrum, light generated by high pressure sodium lamps resembles the natural sunlight during autumn. Due to this peculiarity, HPS light is the best for promoting plants blooming. However, some plants may react negatively to this type of light, growing with oblong stem, etc. To address that issue, new HPS bulbs with color correction have been developed. For example, Son Argo feature properly balanced light spectrum, which suits perfectly for the needs of indoor gardening.

High pressure sodium grow lamps are made of a semi-transparent ceramic arc tube, filled with a mixture of sodium, mercury, and xenon. The arc tube is placed into the protective outer glass shield, similarly to metal halide bulbs. The power ranges of HPS bulbs vary from 35w to 1000w, while the most popular are 250w, 400w, 600w and 1000w.

HPS bulbs are more durable in comparison with MH bulbs: they can be replaced once every 24 months. Though HPS grow lights lose their brightness slowly, in order to keep the brightness at the steady level, it is still recommended to replace the bulb within the specified period.

Among the brand new types of grow lights are sulfur lights, which are said to feature extremely high brightness and effectiveness. However, these bulbs are still rare on the market in view of the high price, so it is early to evaluate their practical value for those gardeners, for whom indoor hydroponics growing remains a hobby.

One can enjoy hydroponics gardening any season of the year, but it is especially rewarding during the cold and dark winter days. Being a type of indoor gardening, this system implies growing of plants in a special growing medium, supplied with nutrient solution, instead of soil. Similarly to other indoor gardening methods, with hydroponics gardening it is necessary to use grow lights, which allow plants to grow, make food and reproduce themselves through flowers or fruits. For this purpose HID lights are commonly used. There are several types of HID or high-intensity discharge lights: for example, metal halide grow lights and HPS grow lights. Every HID light requires digital ballast, which is necessary in order to control electrical current within the lamp, and thus provide its seamless functioning. Supplying light with a reflector is highly recommended as well, since it allows pointing the light in proper direction and increasing the light, produced by the bulb itself. Other type of grow lights are cost-effective and lightweight LED lights, where light-emitting diodes are used to produce light in colors beneficial for keeping up plant growth. The use of any of these lamps is highly effective for hydroponics growing.

Metal halide lamps contain aluminum arc tube, filled with argon, mercury and a variety of specific metals. It is a set of different metals that provide a particular color of the light, produced by the lamp. The argon gas works to start a lamp, when electric current is introduced at the electrodes on either end inside the arc tube. Under the effect of electric current mercury and metals start to vaporize and the light is produced. The key benefit of these lamps is that being small in size they produce a significant amount of light.

HPS grow lights, also known as high-pressure sodium lights, also have an aluminum arc tube inside, similarly to metal halide lights. However, the filling of the tubes is different: in case of HPS there are sodium, mercury, and the Xenon gas inside. Both metal halide lights and HPS lights require ballast for stabilizing electric current and providing smooth performance.

LED grow lights are small, but work very efficiently providing a lot of bright light. In general, they are similar to the lights, used for decorating Christmas tree. The light is produced when electric current moves between the two crystals inside a diode, which works as semi-conductor. Furthermore, LED grow lights usually have a reflector and a lens to direct the light where it is needed.

 Along with being cost effective and energy saving, there are multiple different color spectrums to choose among in order to suit specific plants needs in the best way. So, irrespectively to what type of grow light you choose, it will work accurately and provide effective growth of your indoor plants.  

Complete freedom from environmental factors gives indoor hydroponic gardening its ultimate advantage. All the elements needed for optimum plant growth are provided by the indoor hydroponic gardening system. Light, temperature, pH, CO2 and Oxygen are important factors that should be considered in planning your indoor hydroponic garden system.

 Light and Photosynthesis

 Essential sugars are created by plants through photosynthesis which is the process of converting carbon dioxide, water and nutrients into energy. Light is considered the most important factor because it provides energy for this chemical reaction. Studies show that an increase in light intensity directly increases the amount of sugar produced. This steadily goes up till the saturation point for light is reached by the plant. Increasing the level of light received by the plant should also be considered. Normally, a plant receives around 8-12 hours of sunlight in a day depending on the season. Plant exposure to this amount of light received in a day should be maintained in an indoor hydroponic garden system. Spacing is also important, be sure that they don’t block the light and ensure all plants received equal amount of light.

Plants not receiving enough grow light will have lasting negative effects on its growth even when corrected. Some characteristics are stems which are spindly and elongated leaving them ineffective in supporting plant growth. A decrease in the amount and size of the leaves is also one problem. More damaging effects of improper lighting are a decrease or absence of fruits, decreased overall quality and a change into a yellowish pigmentation for the plant.

Carbon Dioxide also plays a major role in Photosynthesis. Plants utilize the CO2 present in the atmosphere than anything else. CO2 systems are available which increase the levels of CO2 in your indoor hydroponic garden system

Good ventilation should also be considered as they maintain temperature and a steady fresh supply of CO2 and oxygen at all times. Complex setups require more complicated ventilation systems but an oscillating fan set on the same timer as the lights would ensure airflow that eventually allows for optimal plant nutrients in an hydroponic system.

Ebb and Flow hydroponic systems or reservoir systems are one of the easiest to build and maintain. Simplicity and low cost in setting up make it ideal for home hobbyists. Basic setup consists of a growing tray for plants in containers. Usually used with pebbles, perlite and rockwool gardening mediums. Reservoirs filled with water and hydroponic nutrient solutions are placed under the growing medium. A timer controls the amount of water pumped back into the growing tray. The draining action helps provide a steady flow of oxygen to the plants roots. An overflow drain is installed to regulate water height and avoid overflow.

Building Ebb and Flow Hydroponic System

The following hydroponic supplies are required for an Ebb and Flow hydroponic system

Growing Tray

Root protection requires a growing light that shields your roots from light. Plastics are preferred to metals and wood due to its light weight and durability. A thorough check of the growing medium is required to make sure that water drainage is complete. Root rot, pests problems and molds are the main problems encountered by improper drainage.

Plant Pots

Any non-metallic plant pot with drainage holes will suffice for a simple ebb and flow system.

Growing Medium

Ebb and flow systems need no special type of growing medium. Clay pebbles (sometimes called grow rocks) are usually used, they don’t need to be mixed with other mediums. Due to frequent flooding cycles, it is advised that water retention be avoided.

Supports

Support for the tray suspended above the reservoir is needed. The setup of the indoor system would dictate if a simple table or milk tray, or a customized support is required. Something sturdy is what you need for supporting the full weight of your setup. Always include the weight of the water and nutrients in planning. Taking note the mature size and weight of the plants should also be considered. Changing the supports would present an impossible if not very difficult scenario once the plants reach their full growth size.

Reservoir

Any large plastic can be used as a reservoir (rubber tubs and trash cans are also ideal). Rust is the main problem with metal containers.

Drains

Two drains are required for your garden, a drain for the water to return to the reservoir and one for the overflow drain. Fill pipes also serve as a drain pipe, allowing it to run up the same way it came down. Overflow pipes should be designed at the desired maximum level of water for the indoor hydroponic garden system. Be sure that the overflow pipe is large enough to accommodate the amount of water to be pumped out of your grow space. Ideally a figure of 125% to 135% of the amount is desired. This assures a optimum flow of nutrients for the growing medium and avoids salt and mineral to buildup.

Water Pump

Pump size depends on the indoor hydroponic systems needs. The amount of water and distance are factors to be considered for the size of the pumps. Aquarium pumps can be used for most small scale systems.

Timers

The type and cost of timers depends on the specific setup of your gardens need. Hobbyists usually employing a single time schedule can work with a cheap timer readily available at a Home Depot or Lowe’s type store. Larger more sophisticated timers are needed for advance or large scale ebb and flow systems this allows control for more than one section at a time.

Flexible Plastic Tubing

Transparent flexible tubing’s should be avoided to prevent algae build up. Ordinary flexible tubing’s may also be used. 

Care of Ebb and Flow Hydroponic Systems or reservoir systems are one of the easiest to build and maintain. Simplicity and low cost in setting up make it ideal for home hobbyists. Basic setup consists of a growing tray for plants in containers. Usually used with pebbles, perlite and rockwool gardening mediums. Reservoirs filled with water and hydroponic nutrient solutions are placed under the growing medium. A timer controls the amount of water pumped back into the growing tray. The draining action helps provide a steady flow of oxygen to the plants roots. An overflow drain is installed to regulate water height and avoid overflow.

The organic hydroponics system pre-supposes that the reservoir will not supply nutrients to the plants; thus, there will be no need to constantly check the ppm and pH balance of water. It will make wet only the lower part of the medium and the secondary roots. This system gives a gardener an opportunity to grow plants as easy as it is in soil growing without troublesome balancing of the chemicals and pH level of the water.

The technique of the organic hydroponics allows supplying organic nutrients to the upper soil-mixture layer, as in traditional plants growing. The liquid forms of the organic nutrients are mixed according to the necessary concentration and then poured onto the top of the medium upper half.  Beware, though, of pouring too many nutrients!

This experiment will help you learn how much liquid with hydroponics nutrients you should pour on your plants for its excess not to drip into the lava rock layer and, consequently, into the water reservoir. If you find out that there is an excess of feeding liquid and it drips through the lava rocks into the grow bed, you can either soak it up with a cloth, or you can use other form of fertilizer, the one without liquid. It is also reasonably to change lava rock.

However, if only a small amount of organic nutrients is noticed to drain into the reservoir, there will be no problem, as the volume of water there is much larger. Reservoir water should be changed every 1-2 weeks, similarly to the standard hydroponics nutrients chemical reservoirs

A great indoor garden requires a good grow light. It could mean the difference between success and failure. Having the right hydroponic light is the single-most important and costly decision in setting up your garden.

 Hydroponic grow lights come in three main types:

Incandescent lights

These are the usual lights found in homes. They are generally a poor choice for garden grown lights because of their limited light spectrum and inefficiency.

HID (High Intensity Discharge) grow lights

Producing more light (up to 10x more lumens/watt than an incandescent light),are more efficient. Drawbacks would be, they produce more heat, generally more expensive than incandescent lights and requires the additional expense and maintenance with ballast. It takes around 100 hours before hydroponic HID grow lights reach their optimum working conditions, or until they reach light intensity and color stability. 

Natural Sunlight

Expense for acquiring artificial lights can be skipped by using sunlight. This is done with the use of solar room, greenhouse or large windows which allows plenty of sunlight. Or you can do this outdoors; hydroponics does not necessarily mean the cultivation of plants indoors but it growing plants without the use of soil.

Basic setup for an indoor garden is 1000w of lighting for and area of 16-25 square feet of plant area. Reflectors and/or light movers should also be considered as they improve efficiency of the indoor hydroponic gardening system. Ballast may also be needed as numerous hydroponic grow lighting require igniting.

 Some Basic Facts

Before plugging in your grow light

Different plants require different levels or types of lighting, this paragraph would deal on some simple know-how on how to make an effective lighting setup. In setting up your garden, it is essential that you determine your growing area in order to determine the best lighting setup for you. Light is an essential factor in the growth of plants, it is important that the lighting solution you chose for your garden is adequate for its size. A poor or ill advised decision would certainly reflect on the quality of plants you produced. Inappropriate budgeting like cost cutting specially on lighting would just prove to be uneconomical and inefficient in the long run.

A general rule for lighting that area coverage is determined by a light wattage output. Reflectors might be used to increase the light area and reach corners but effectiveness is still determined by this formula.

Day and Night Cycles

The type of plant and its stage of growth generally determine the amount of light needed. A common cycle is that with 18 hours of light and 6 hours of darkness which is recommended for its vegetative growth phase.

For seedlings, a continuous light source is needed until the first real leaves appear. When the leaves appear, the regular 18/6 light cycle is used. Fluorescent or incandescent lights are best for seedling because of the low heat and soft light they generate. Automated timers maybe used to ensure consistent light cycles. Inexpensive timers are also available; this can be found any hardware or Home Depot/ Lowe’s type store.

Light and Photosynthesis

The plants exposure to light intensity, duration and light color directly affects the amount of energy needed for photosynthesis. The color of the light, Blue simulates the summer sun, Orange for autumn seem to stimulate photosynthesis best. The light spectrum produced by metal halide bulbs (Blue lights) and high pressure sodium bulbs (red/ orange lights) produce this effects. HID grow lights produce these effects owing to their popularity to hobbyist and professionals. Combination of metal halide and high pressure sodium bulbs provides the complete spectrum of light produced by the sun.

Use Caution When Working with Lights

The combination of water, electricity and chemicals in such a closed-in space makes the grow room one of the most dangerous places in your house. Keep in mind to separate your ballast by elevating it from the water-containing areas of your hydroponic growing system. 

Along with water,  hydroponics plant nutrients, Co2 and oxygen, grow lights is the key basic component, required by plants to live. Providing additional light is necessary for indoor gardening. Furthermore, light should resemble the sunlight as much as possible. In order to achieve that goal several types of lights are used: incandescent, fluorescent, high intensity discharge or HID lamps and sulfur lights. While there are many other types of lighting, only the mentioned above are recommended for indoor gardening. The major concern with other types of lights is that they do not produce light in the appropriate spectrum, required by plants.

Though typical widely used incandescent lamps fit any ordinary light socket, this type of lighting is considered to be the least effective in lighting your garden in comparison with other types of lighting. Incandescent lights produce light in the red spectrum; that is why such lamps are commonly covered with a blue coating in order to increase the amount of blue spectrum in the produced light. In general, incandescent lights are considered to be poor options for indoor gardening needs.

In comparison with incandescent lamps, fluorescent lights produce more light with lower energy consumption. However, the light, produced by fluorescent lamps, is not intensive enough and cannot penetrate more than 6” – 8”. Light, produced by fluorescent lamps, is usually simply insufficient to provide normal growing of plants, vegetables and flowers. The only application, where it is possible to use fluorescent light, is growing seedlings, cuttings, or some particular plants with low light requirements, such as orchids.

High intensity discharge lights, also known as HID lights, are currently the most effective lights for indoor gardening. Metal halide (MH) and high pressure sodium (HPS) grow lamps are two major types of HID lights. Each type produces light in a particular range: for example, metal halide lights generate blue spectrum light similar to the full summer sun, and high pressure sodium lights produce light in red and yellow spectrum, resembling the autumn sunlight. 

Though high pressure sodium lamps usually are more expensive (by about 10%-20%) than metal halide lamps, they are more durable with extended lifecycle. Besides, HPS lights feature higher lumen output (97-150 lumens per watt consumed) and lose only about 5% of their brightness after one year of use (for comparison, MH bulbs produce about 70-115 lumens per watt and  lose up to 15-20% of their initial brightness within a year). 

Irrespectively to the particular type of lighting in use, it is recommended to replace lights on the timely manner: MH bulbs – after 12-18 months, and HPS bulbs – after 24 months of work. Basically, metal halide lamps is the more preferred type of lighting for plants, when they grow, and high pressure sodium lamps suit best for flowering plants. However, the discussion on which type of lighting is best is still open among gardeners. Each type of lights offers its own advantages, as well as disadvantages, so it is often a matter of personal choice, preferences, growing environment and needs. The scope of this article is to provide plain information on the available types of lighting for indoor hydroponic gardening, while leaving readers enough space for personal decisions on which product to prefer.  By the way, recently a new type of lights appeared. The so-called conversion systems allow switching between MH and HPS lights when it is necessary simply by changing the bulb. Though this type of lighting offers certain benefits, conversion systems are still pretty expensive. More information on particular types of HID grow lights used in hydroponics systems will be provided in the next set of hydroponics guides.