What is hydroponics?

"Hydroponics is the art of growing plants in water.
You will find more information about hydroponics here."

I'm new to hydroponics, what do I need to get started?

"To get started, you will need a hydroponic system, specific nutrients, a substrate (depending on the hydroponic system used), a light source (natural or artificial), time and plants.
Download our guide to getting started in hydroponics: The Basics.
To find out more, read William Texier's article on the different growing systems (in English)."

Where can I grow plants using the hydroponic method?

"Everywhere…Indoors, in a greenhouse, in a grow cabinet or outdoors. The vast majority of plants grow using hydroponics, even if some plants are more delicate than others."

What is the difference between your hydro and aero products?

"In a hydro system, the roots grow fully in a neutral substrate, which is continually irrigated with an oxygenated nutrient solution.
In an aero system, the plant grows exposed roots in a mixture of air and nutrient solution, which is also oxygenated.
The presence of a substrate in a hydro system allows you to contain any potential feeding errors and to have the time needed to rectify these mistakes as a result. On the contrary, in an aero system, as the roots are exposed, the slightest feeding error will have immediate, and potentially disastrous, consequences for the plant."

What's the point of growing my plants using hydroponics rather than in the ground?

"In hydroponics, the plant receives all of the nutrition it needs directly, according to its stage of development. As the plant has no need to search for its food, it will grow fewer roots and put all of its energy into producing more leaves, flowers and fruits. It is thought that, by using hydroponics, you can achieve up to 30% greater production than in the ground.
For more information, see here."

Will my crop taste different using hydroponics to if it was grown in the ground?

"If you carry out industrial growing in huge greenhouses, if you use hardly-purified raw materials and if the nutrition and management of the crop are done by computer, or if you choose species for their appearance rather than their taste, you will achieve tasteless and scentless crops.
However, if you have a small urban garden or a family farm, you use quality products and you manage the crop yourself, you will achieve products full of flavour and aroma.
(To read: Urban Garden(ing)"

Is there an application chart with specific dosages per plant?

"Yes, it can be downloaded here, but you can also contact us if you cannot find the plants that you are growing."

Do I need to keep the packaging for my system?

"No, it is not necessary to keep the packaging. However, each package has a serial number on it, which may be useful if you need to contact the after-sales service team. We therefore advise you to keep it."

Why don't you have the same application charts as General Hydroponics (US)?

"This is because, culturally, North American growers work with a higher EC."

Do you manufacture all of the plant nutrients?

"Yes, all GH nutrients are manufactured in France at GHE premises. There is one exception: FloraNova is imported from GH in California, who hold a unique manufacturing process, which allows such a level of concentration to be obtained."

Hydroponic systems

I'm new to hydroponics, which systems would you recommend?

"Our AquaFarm, WaterFarm and EcoGrower are good systems for beginners. Almost all plants can be grown in these systems and if, later on, you decide you want to have additional units, the small systems can be connected to each other and to our ACS controller."

Which is the best system for starting off cuttings?

"Our RainForest series and the CuttingBoard are recognised as being among the best propagation systems in the world."

Which is the best system for growing tomatoes, peppers and cucumbers?

"These plants have a longer growing season and need enough space for optimum root development.
Our best systems for growing these crops are the WaterFarm and the EcoGrower, without forgetting the AeroFlos, which have proven themselves time and time again!"

Do I need to leave my system running 24/7 or do I need to run it on cycles?

"All of our systems are designed to operate 24/7 in order to obtain optimum results.
Energy saving and the disturbance that the noise may cause during the night if you sleep close to your systems are the only reasons for stopping the system from running.
In this case, and once the roots are long enough to reach the nutrient solution, you can turn off your system and turn it back on for 1/2 hour in the middle of the night cycle. For this, you need to get a programmer to connect directly to the power point.
There are also some plant species that do not need to be watered 24/7, for example cacti."

What is the ACS controller and what is it for?

"The ACS controller is a central reservoir that supplies several WaterFarms or AquaFarms with nutrient solution. Its distinctive feature is that it has active circulation i.e. thanks to its dynamic circulation system, the nutrient solution performs a complete circuit approximately every two hours, allowing the nutrient solution in each reservoir to be circulated and perfectly oxygenated. The other advantage of the ACS controller is that it regulates the level of nutrient solution in the connected reservoirs, which allows the aquatic roots to be protected."

My system is very dirty, how do I clean it thoroughly??

"Between crops, you need to give the whole system a good clean before starting a new cycle. Use FloraKleen.
If your system is particularly dirty, fill it with a very acidic solution (pH below 4.0) and let the system run for an hour. Then, rinse thoroughly. In the event of disease or insect attack, use a household disinfectant (chlorine) to clean the system well. Rinse and allow to stand for 24 hours so that the chlorine evaporates completely."

How do I prevent the accumulation of algae in my hydroponic system?

"Prevention is the best method. Keep the nutrient solution away from light and cover the surface of your pots with a protective disc."

Is it possible to obtain parts for old GHE systems?

"Yes, you can order parts:
- Either at your local shop, which will order the parts for you.
- Or directly with us by sending an e-mail to info@eurohydro.com or by calling +33 with the name and a description of the parts. We will then let you know as soon as possible about availability and prices. If you kept your assembly instructions, you will find the references for all your parts there."

Are the plastic components used in the General Hydroponics Europe systems likely to release chemicals that may contaminate the plants?

"No, all of our plastic parts are inert. There are no chemicals that infiltrate the plants. The plastics are also stabilised against UV rays."

Do I need a humidome for my RainForest system?

"No, you do not need a humidome. The Vortex motor, included in all of our Rainforest systems (72, 66, 318 and 236), provides the humidity and oxygenation required at the root zone, by means of an ultra-fine and powerful mist of nutrient solution. These are the most reliable propagation systems in the world. However, you must keep the temperature at a minimum of 22° and the humidity at 70%."

What is the capacity of the WaterFarm? What happens if the solution goes beyond the basket and touches the clay pebbles?

"Our WaterFarm has a maximum capacity of 15 litres. The ideal fill level is approximately 12 litres, just underneath the basket. However, if the solution level goes beyond the basket, it is not a problem."

Why is there not a diffuser for each plant in an Aeroflo growing chamber?

"The level of solution in the chamber is generally adjusted so that 2/3 of the root mass is submerged. Diffusers are made to oxygenate the nutrient solution, by spraying drops into the air, stimulating circulation of the solution and cascading down the walls of the chamber. The diffusers are not made to water each plant individually. It is recommended that you position the diffusers towards the walls of the growing chamber and not towards the roots."

The pots in my Dutch Pot Hydro (or Panda Hydro) get clogged up.

"This phenomenon occurs when the root mass is too large, the rootlets follow the flow of water and block the siphon elbow. This problem can only be solved by manually unblocking the siphon, which risks damaging the roots. Instead, we recommend that you take preventive action by slightly increasing the EC of the solution, which will limit the development of the root mass."

How can I easily empty my AquaFarm/WaterFarm or AeroFarm?

"You can simply lift the system and tilt the level tubes."

The low AeroFlos (56 and 84) are not equipped with active circulation between the reservoirs. Is this normal?

"Yes, this is normal. The secondary reservoir (without pump) functions as a controller. It is imperative that fresh solution is added in the latter."

Can I convert a Dutch Pot Hydro into a Dutch Pot Aero?

"There is a conversion kit for the 1m² version under reference SYS81001. However, the conversion of a Dutch Pot Hydro 2m² into a Dutch Pot Aero 2m² requires changing too many parts and, therefore, it is better to sell your system and buy another."

I have a Rainforest² , can I change versions?

"Yes, we sell the pots and inserts separately, which allow you to move to a 36, 18 or 6 plant version. You can find out more from your retailer."

I am having difficulty in placing the level tube (grey) on my AeroFlo growing chamber?

"Use some water or a silicone spray."


What are expanded clay pebbles?

"They are small balls of clay baked at a high temperature, which are used to support the plant. They have excellent drainage properties. Quality pebbles must have a neutral pH (7.0) so as not to increase the pH of the nutrient solution. We recommend that you rinse the pebbles before first use.
See page 40 of our catalogue (which can be downloaded here)."

What is rockwool?

"Rockwool comes from basalt, a black volcanic rock found in many regions of the world. The manufacturing process for rockwool is similar to the natural activity of a volcano. The volcanic rock melts in a heated coke oven at 1,460°C. The molten rock is then turned into fibres by wheels turning at high speed (see Wikipedia)."

What is coco peat?

"This substrate is made from coconut residues: impurities, short fibres and the soft part of the husk, which are dried and then compressed into slabs, blocks or pellets."

What is the difference between expanded clay pebbles and coco peat?

"Clay pebbles are made from expanded clay, which is of mineral origin, whereas coconut peat is an organic product. Clay pebbles ensure good drainage and ventilation, whereas coco peat retains moisture."

Does the type of substrate chosen (clay pebbles, rockwool, coco fibre etc.) change irrigation times?

"Yes, of course. There are three mayor types of substrate: those which retain moisture, such as coco fibre, draining substrates, such as clay pebbles, and water, the hydroponic substrate par excellence. Depending on the water retention capacity of the substrate, the time period for which it is necessary to stop irrigation will be longer or shorter. For example, with clay pebbles, you should keep your pump on all the time, whereas you will need to stop irrigation at times with rockwool and coco fibre. Use a timer to make this easier.
See page 40 of our catalogue (which can be downloaded here)."

Can I do without a biofilter to keep living microorganisms in a hydroponic system (Trichoderma for bioponics or SubCulture)?

"To stay alive, microorganisms need a porous, moist and oxygenated environment in order for them to colonise. After a number of tests, we recommend that you make a mixture of 70% clay pebbles and 30% coco fibre.
However, in aero-hydroponics, the use of a Biofiltre (biofilter) is compulsory as the total volume of substrate is insufficient."


How important is water quality in hydroponic growing?

"It is vital. It is the hydroponic substrate par excellence.
The hardness of the water (hard water contains a high level of calcium and magnesium) must be taken into account when choosing nutrients. There are nutrient formulas designed for hard water and we recommend that you use these if necessary. To find out about the quality of your water, contact your water provider who will provide you with a water analysis free of charge. You can also download our water quality maps (link to download).
If your analysis shows a calcium content of greater than 70ppm (mg/litre), use FloraMicro or FloraDuo Grow (hard water) formulas. To ensure the quality of your water, you can also use rainwater or install a reverse osmosis filtration system. In these two cases, mix approximately a quarter-litre of tap water with your filtered water to restore its buffering capacity. Do not use mineral water as it destabilises the nutrient solution and may even be toxic to the plants.
In France, water hardness is measured in TH degrees.
See page 44 of our catalogue (which can be downloaded here)."

My water is chlorinated. Is this a problem?

"Chlorine is volatile and evaporates quickly. If your water contains too much chlorine, we recommend that you keep the water in an open container overnight so that the chlorine evaporates and only use the water the following day."

What about water temperature?

"This is another critical factor in hydroponics. It is important to know that the warmer the water in your reservoir is, the less oxygenated it is. As high temperatures promote the development of pathogens, you should, as far as possible, keep the temperature of your water between 18 et 26°C. Use microorganisms such as trichoderma harzianum or the SubCulture mixture of bacteria and fungi to help the roots withstand the heat. See page 44 of our catalogue (which can be downloaded here). When adding water to the reservoir, it is best to make sure it is the same temperature as the water already in the reservoir. Plants do not like change, especially in the root zone."

Does the pH level give an indication of water hardness?

"No. Water hardness is calculated by measuring its concentration of calcium and magnesium whereas pH indicates the concentration of H+ ions. These two values have no correlation."


Do I need to shake the nutrients before using them?

"Yes. Our nutrients are highly concentrated and it is recommended that you shake them before use."

Can I mix the concentrated nutrients together and then add them to the water?

"No. This causes the different components to crystallise. Therefore, each nutrient should be poured separately directly into the water."

Do I need to rinse my measuring container every time I change between components?

"Yes, to avoid precipitation when making your mixtures."

What is the shelf life of your nutrients? Is there an expiry date on the bottles?

"The shelf life of the nutrients depends on the conditions under which the products are stored. The nutrients should be stored away from light for optimum shelf life. Therefore, there is no expiry date."

Why is Flora Series made up of three parts?

"The idea of a three-part nutrient was invented by GH in 1976. Each of these three parts has a specific function. By using different combinations of FloraGro, FloraBloom and FloraMicro, the grower is able to meet the exact needs of his/her plants as they grow and to make specific adjustments to create suitable nutrient mixtures.
- FloraMicro, the base solution of the Flora Series, provides nitrogen, magnesium and calcium, as well as trace elements, which are essential for comprehensive nutrition in hydroponic growing.
- FloraGro contains elements that are essential for the vegetative cycle and, therefore, by adding FloraGro to FloraMicro, the plant receives additional nitrogen, potassium, magnesium and sulphur, which stimulates structural and leaf growth.
- FloraBloom contains phosphorus, which is necessary for flowering and fruiting, as well as sulphur for aromas."

What are the recommended nutrient dosages?

"The correct ratio of Flora Series nutrient depends on the plant being grown and its growth stage. On our website, there are also application charts for hydroponics and for soil, as well as a nutritional programme for some relatively common plants."

Is Ripen a P-K 13-14?

"No, not at all. Ripen is a formula in its own right. It is a nutrient used at the late flowering stage and is designed to accelerate ripening and increase the content of active principles. It is used on its own and also eliminates the traces of mineral salts that may have been deposited in the plant."

Can I use FloraNova Grow and FloraNova Bloom at the same time?

"FloraNova is a one-part nutrient. You would usually use FloraNova Grow on its own during the vegetative stage and FloraNova Bloom during the growth and flowering period.
However, during transition periods (growth to flowering) and with semi-cuttings, you can mix half and half from each of the bottles, which will give you a more comprehensive solution."

Can I spray GH products on the leaves of my plants?

"Of course. Make sure that you maintain a low EC (electrical conductivity) value of 0.4mS. Do not spray GH products in the middle of the day or under too bright light. The best times to spray leaves are early in the morning or late in the afternoon. It is best to spray under the leaves for better absorption."

Can I use GH nutrients in soil?

"Of course! You can use them in open soil or in pots. A nutrient designed for hydroponics is generally comprehensive and highly soluble. The nutrient will be just as effective and you will need to use 50% less! All of our nutrients contain all of the elements needed for plants to grow. Start by first adjusting your dosage according to the advice on the label and then adjust the mixture according to the needs of your plants.
Refer to our application charts for hydroponics and soil."

What are the advantages of bioponics compared to hydroponic growing and soil-based growing?

"The appearance of plants grown using bioponics will be different to that of plants grown using hydroponics. Less green mass and a yield of 15% to 20% less. On the other hand, the appearance, taste and scent will be the same as those of plants grown in soil. The advantage of bioponics is that it combines a quick growth cycle, as found in hydroponics, with the taste quality of soil-based growing."

Can I use hydrogen peroxide (h3O2) to maximise the oxygenation of my nutrient solution as part of bioponic growing?

"No, because it would kill the bacteria responsible for decomposing organic matter. However, you can use an air stone in the central reservoir."

Are the American and European formulas for the Flora Series the same? If yes, why are the NPK values different?

"The Flora Series formulas are the same in the USA and Europe. The difference in NPK values is the result of a difference between American and European legislation."


What is pH?

"pH is the measure of the acidity/basicity of a solution.
More precisely, pH is a measure of H+ ions. pH is measured on a scale from 0 to 14. Pure water has a pH of 7.0.
If the pH is less than 7, the solution is acidic. If the pH is greater than 7, the solution is alkaline or base. You can find more information on pages 28-29 and 44 of our catalogue (which can be downloaded here)."

How does the pH level affect plant growth?

"The pH level is important because it affects the availability and absorption of the elements needed for plants to grow. For the most part, nutrients are absorbed in higher quantities when the pH is between 5.5 and 6.5. When the pH level falls outside of this range, some elements are less available, thus resulting in incomplete, or even deficient, plant nutrition.
See pages 44-45 of our catalogue, which can be downloaded here."

How can I adjust the pH?

"pH is adjusted by using an acid (pH Down) to lower pH or by using a base (pH Up) to raise pH. The pH Down and pH Up are designed for this purpose. These products also contain buffers, which stabilise pH over a long period.
See pages 44-45 of our catalogue, which can be downloaded here."

How often should I check my pH level?

"As pH is a crucial factor in plant nutrition, it is recommended that you check your pH level every day. There are several factors that may alter the pH level. For example, if your plants are in full growth mode and are consuming a lot of food, the pH will fluctuate greatly, even if you have a stabilised nutrient to begin with. However, you do not have to readjust the pH all the time; you can allow the pH to fluctuate between 5.5 and 6.5."

What quantities of pH Up/Down should I use?

"Follow the instructions on the label. It is recommended that you add pH regulators to the solution in small quantities because they are very concentrated. Add a little bit at a time, mix well and then measure the pH until you obtain the desired level.
Please note that the Flora Series contains regulators in order to make it easier to keep the pH within the optimum range."

The pH of my solution falls to 4 a few days after every clean and refill. How can I raise the pH and stabilise it?

"A pH that drops is a sign that there is too much microbial life, not necessarily pathogenic, and dying microorganisms acidify the solution. The simplest way to raise your pH level is with tap water, if it is of an acceptable quality. Otherwise, you can add pH Up. Avoid excessive fluctuations in pH and EC."


How important is the conductivity of the nutrient solution?

"Conductivity measures the concentration of the nutrient solution and, therefore, must be adjusted to the needs of your plants. The higher the conductivity, the richer the solution is in nutrients. Put simply, if the conductivity is too low, this can lead to deficiencies, whereas, if the conductivity is too high, this can lead to toxicity.
Delicate plants, cuttings and seedlings need a low conductivity. Once the plants begin to grow, they need a more concentrated nutrient solution. Therefore, conductivity must be increased by adding nutrients. Some plants prefer less concentrated nutrients whereas others grow better with a higher concentration."

What is the best way to measure electrical conductivity (EC)?

"Unlike pH, which can be very accurately measured with a liquid pH indicator, there is only one good way to measure conductivity: using an electrical conductivity meter. The type of meter you choose is very important: you should opt for quality, you will not regret it. You should calibrate your device regularly with calibration solutions intended for this purpose."

What does an EC meter measure? What about a TDS meter?

"EC (electrical conductivity) measures an electrical value in millisiemens (mS), whereas the TDS converts this measurement into parts per million (ppm in mg/L).
EC meters are used in Europe and TDS meters are used in North America."

I would like to know whether the dosages listed on the bottle include the EC of the tap water or whether I need to add this to the dosages indicated.

"If you have an average conductivity (0.4-0.6), you can increase the conductivity indicated by 0.2."

Problem prevention and resolution

How do I prevent root infections?

"The best prevention method is to use a balanced and perfectly-oxygenated nutrient solution. Keep your nutrient solution between 18 and 26°C to ensure good oxygenation.
To protect your plants against root infections, use our SubCulture or BM, which protect the entire root mass with a protective mycelium. They occupy the ecological habitat of pathogens and prevent the pathogens from taking hold."

Can I use Mineral Magic with SubCulture?

"In hydroponics, do not use Mineral Magic at the same time as microorganisms (BM and SubCulture). This would be counter-productive as the silicate dissolves in the water to form silicic acid, which slows down the development of beneficial colonies. On the other hand, when mixed in soil in a powder form, the wide range of elements contained in Mineral Magic stimulates the growth of beneficial microorganisms and, therefore, helps to create a natural environment for growing even healthier plants."

Can I use enzymes with SubCulture?

"It's not necessary because the bacteria in SubCulture produce enzymes continuously in the quantities needed for your crops."

My plant is deficient, what should I do?

""Real" deficiencies rarely occur in hydroponics, assuming that you use nutrients that are specifically formulated for this type of growing and that you follow the growth programmes. Visible symptoms do not always indicate a nutritional issue but are often linked to a change in the plant's environment, which will affect the absorption of nutrients and lead to one or several deficiencies. These are known as "secondary deficiencies".

Therefore, before putting the symptoms down to a real nutritional deficiency, you need to check all environmental factors: oxygenation of the solution, pH levels, EC, temperatures (both external and of the solution), light, condition of the roots or presence of pathogens...

In every case, the treatment is always the same: empty the system and discard the nutrient solution. Fill your system again with pH-adjusted water without nutrients. You could also potentially add a root stimulator to the solution to help the plant develop a healthy root system and provide a leaf fertiliser in the form of a light nutrient solution (the same as that used for seedlings)."

I decided to opt for this system (BioFiltre and SubCulture) as a preventive measure because I recently had what I understand was a fusarium (brown, even rust-coloured, colouration of the roots, a halt in growth with signs of over-fertilisation). Do you know of this pathogen and do you know if SubCulture can really help attacked plants to recover?

"Yes, we do know of this pathogen. It is best to use SubCulture as a preventive measure. However, it can also work as a treatment if you stimulate the growth of new roots by using a product like our Bio Roots at the same time."

Do I need to empty the reservoir and refill it with fresh water and nutrient solution?

"Especially for beginners, and even for experienced growers, we recommend that you empty the reservoir every 10 to 14 days, depending on the size of the plant and the quality of the nutrients used. It is also a good idea to rinse the clay pebbles every time you clean the reservoir."