There are many kinds of hydroponic equipment. Except for some particularly simple hydroponic systems, most hydroponic systems require water pumps to circulate the nutrient solution. The circulation of nutrient solution is very important. The air enters with the circulation of the nutrient solution through porous sand filter stones (sand heads for short) to supply oxygen to plant roots. The water pump, its supporting pipes and the devices connecting the two are the core of the hydroponic system, and growers need to focus on these aspects in the procurement process.
(The “feel” mentioned below is the name of the diameter of the imperial pipe. Usually, the “feel of the pipe” refers to a few eighths of an inch (1 inch = 25.4mm). Commonly used are two points and four points. The inner diameters of the minute, six-point, and one-inch tubes are 6.4mm, 12.7mm, 19.1mm, and 25.4mm respectively.-Translator’s Note)
Irrigation
“Irrigation” is another term for “watering”, but in hydroponic systems, irrigation is not as simple as conventional watering. Irrigation equipment is not only a tool to provide water and fertilizer, but also an important part of the hydroponic system. To build a system with irrigation function, the following two devices are required: water pump (generally divided into two types, one with filter The other is a five-filter pump) and pipes. The pumps are used to suck water and provide power for the circulation of water, and the pipes are used to transport water.
Water pump
The main factors that need to be considered when choosing a water pump are the pump lift, flow rate and the size of the water delivery port. Many systems only require a suitable pump to deliver water to a specific height. For example, if the grower needs a water pump that can be used in a tidal system, he should pay attention to whether the pump lift is greater than the distance between the pump outlet and the seedbed. In the nutrient liquid film cultivation system and spray culture system, when the water flow rate is the same as the pump flow rate, the whole system will achieve the best effect, so that neither the water overflow due to the pump flow rate is too large, nor the water pump flow rate. Too small leads to insufficient water supply. For these systems, the important consideration is that the head of the pump will affect the flow rate of the water. For the same water pump, when the distance between the pump and the water outlet is 1.2 meters, the water delivery speed is 2.3m³/h, and when the distance reaches 3m, the water delivery speed is 0.72.3m³/h. The number of drip arrows (drip irrigation drippers) will also affect the flow rate of the water. It is best to choose a pump with a higher power. In addition, the valve can be used to reduce the flow rate, but not to increase the flow rate.
Air pump
The air pump can not only inflate the nutrient solution to increase the content of dissolved oxygen in the nutrient solution, but also ensure that the nutrient solution in the storage tank is evenly mixed. Although plants produce oxygen, they also consume oxygen by performing various life activities, such as the process of water absorption by the roots. If there is not enough oxygen around the root system, the root system will not be able to absorb water and supply the leaves upward, and the plant will wilt. Increasing the oxygen content around plant roots can make plants more robust and effectively increase yields.
The airflow rate of the air pump is in L/min. The air velocity required by the hydroponic system is affected by many factors, such as the size of the reservoir, the water temperature, the type of crop, and the growth period of the crop. Under normal circumstances, a 19L water storage tank and an air pump with an airflow rate of 1L/min can provide sufficient oxygen.
Sand head
When the air pump passes through the sand head, the air is input into the nutrient solution, and the sand head has various shapes and sizes. Growers can screen according to their own needs. The author likes the sand head with a soft texture and a suction cup at the bottom. In addition to the Venturi pump and the air pump-sand head device, there are other ways to aerate the nutrient solution. In the nutrient liquid film cultivation system, the nutrient liquid waterfall (the nutrient liquid falls from above) is usually used to aerate. Of course, there are also more cashier methods, such as synthesizing ozone and adding liquid nitrogen.
Pipeline
Irrigation pipes are of various kinds. Traditional irrigation pipes used for landscaping are usually very hard, which is not easy to use in hydroponic systems. Black vinyl pipes are flexible, strong, and widely applicable, and are favored by growers. The inner diameters of common black vinyl tubes are 6.4mm, 12.7mm, 19.1mm, 25.4mm, commonly known as two-part, four-part, six-part，and one-inch pipes.
It is not recommended to use transparent pipes. Because of light transmission, the nutrient solution tends to breed algae and affect the normal growth of plants. But the transparent pipe is very popular in the aquarium because it looks transparent and beautiful, and does not affect people’s viewing of the plants and animals in the aquarium. If you don’t care about the beauty, a black pipe of the same size has the same effect as a transparent pipe.
Accessories
Irrigation and drainage accessories
Growers can use irrigation and drainage accessories and some ordinary household plastic containers such as plastic boxes to make cultivation beds. The accessories we usually refer to include four-point water supply accessories, six-point drainage accessories, pipes，and filters.
Sealing ring
It is one of the most useful irrigation accessories in DIY hydroponic systems. Whether the sealing ring can seal irrigation has not been seen to prevent water leakage. Sealing rings are generally used for PVC pipes, plastic boxes, buckets, hydroponic planting areas, and liquid storage tanks. Its size is usually 12.7mm and 19.1mm, commonly known as four-point rubber sealing ring and six-point banana sealing ring.
Pipe connector
It is similar in appearance and function to the pipe connectors used in daily households, but is smaller in size.
Basin and tray
Net basin
The shape of the mesh basin is square or round, usually 5-25cm wide. The most commonly used net pot diameters in DIY soilless culture systems are 5cm and 7.5cm.
Round plastic basin
The most common and easily available.
Square plastic basin
The distance between the basins can be reduced to maximize the use of space. The square plastic basin is easy to pack and is favored by people.
Plastic cultivation bag
It has long been used in commercial farms, and now it has also begun to enter the home vegetable garden. Plastic cultivation bags are difficult to reuse, but they are inexpensive. The mouth of the cultivation bag can be rolled up to adjust the volume of the bag. When there is no substrate, the cultivation bag is square; when it is full, it is cylindrical.
Non-woven cultivation bag
They are very suitable for soilless cultivation because they drain quickly and do not expose the substrate. In addition, the non-woven cultivation bag can be reused. Just empty the bag, turn over the inside of the bag, and after drying, brush off the remaining debris. The non-woven cultivation bag can also be washed in the washing machine.
Pottery basin
It is not common in soilless culture, but it does not mean that pots cannot be used. The wall of the pottery pot is hollow and has good air permeability. This feature is similar to that of the non-woven cultivation bag. Unlike non-woven cultivation bags, pots are heavier and easy to break.
The color of the pot
Indoor growers prefer white flowerpots because the surface of white flowerpots is highly reflective and can reflect more light to the plant canopy. Outdoors where the temperature is high, the white pot is also very popular because it is not easy to absorb heat; but in a cold environment, the black pot is more conducive to increasing the temperature of the rhizosphere of the plant.
Tray
The pallets come in various sizes, depths and colors. Standard sizes are 0.3mx 1.0m, 0.6mx 0.6m, 0.6mx 1.2m, 0.9mx 0.9m, 1.2mx 1.2m, 0.9mx 0.9m, 1.2mx 1.2m, 0.9mx 1.8m, 1.2mx 1.8m, 0.6mx 2.4m and 1.2mx 2.4m.
Liquid storage tank
The volume of the liquid storage tank is usually 70-450L. The plastic storage tank is light, durable, resistant to sunlight, and not easy to age, and has a matching cover with a window that can be opened and closed.
Cultivation substrate
The growth rate of crops and the success or failure of planting are affected by the porosity of the cultivation substrate and the strength of the respiration of the crop roots. The grower can choose the cultivation substrate according to their own needs. For beginners in soilless cultivation, improper watering during planting is the most common problem. In clay or poorly drained flower pots, excessive watering can drown the plants because the root system needs oxygen to absorb water and nutrients. When the root lacks oxygen, the plant will not be able to absorb water, and the above-ground part of the plant will wither. In addition, excessive watering will increase the probability of root diseases, so try to avoid excessive watering.
Growers can choose a substrate with weaker water retention to increase the oxygen content of the root environment, but this requires frequent or continuous irrigation to ensure the root water supply. Some growers prefer to use water-retaining substrates to reduce the frequency of irrigation. The strong water-retaining substrate can also improve safety and stability, and prevent plants from being injured due to power outages, water pump failures, or untimely irrigation. In a warm and sunny environment, plants grown in porous substrates (such as ceramsite) may be damaged or die if they are not irrigated in time for only a few hours, while plants grown in coconut bran (coconut bran are more water-absorbing Strong) can grow normally for a few days without irrigation. However, this increase in safety will also affect the growth rate of plants, and the growth of plants is slow.
Seedling substrate
The seedling substrate introduced in this book is a mixed substrate composed of grass charcoal and coconut bran, and the other is rock wool. There are many other types of seedling substrates, but these two substrates are most suitable for beginners because they have good water holding capacity and are not easy to cause waterlogging.
Rock wool
It is made by melting basalt and drawing “magma”, which is similar to marshmallows, but the taste is very bad (disclaimer: don’t eat rock wool!). Rock wool is very popular in commercial or domestic soilless cultivation because it has a good balance between water retention and porosity. It is very suitable for beginners and can avoid damage to plants caused by excessive watering. Some substrates have strict requirements for the amount of watering, but rock wool does not have high requirements for the amount of water. After excessive watering, the growth of the plants growing in rock wool may deteriorate, but they will never die. Rock wool has various shapes, such as block, plate, and loose.
Coconut Peat
Cultivation substrates made from coconut shells are widely used in conventional and nutrient-liquid cultivation modes. If the coco peat is not properly washed during processing, the salt content of the coco peat will be high, which will harm crops that are sensitive to salt. Therefore, the correct way is to rinse the coconut bran before use to remove the residual salt, and also to rinse away the tannic acid and other substances that may contaminate the storage tank and crop growing area.
Fine coconut bran
Also called coconut shell powder, it is a good material with strong water holding capacity. It is usually used to replace or mix with peat charcoal. It is different from grass charcoal in that the initial pH of coconut bran is suitable for most vegetable growth needs, so there is no need to add lime to adjust the pH. Like grass charcoal, coconut bran is usually mixed with perlite or other porous substrates to reduce the weight of the mixture and improve the drainage performance of the substrate and improve the water retention performance of the substrate.
Coconut shell flakes
It is very thick and has good water retention and drainage capabilities. Coconut shell flakes can be used alone or mixed with other substrates. When coconut shell flakes are used alone, they need to be watered frequently, which is similar to the irrigation method of growing plants in ceramsite.
Perlite
It is made by heating the volcanic rock until the volcanic rock bursts like popcorn. Perlite is very lightweight and is widely used in the construction industry. Perlite is used for horticultural planting because it is cheap, light, and very suitable for mixing with poorly air-permeable substrates such as grass charcoal and coconut bran to increase its air permeability. The particle size of perlite has many specifications, ranging from fine particles to massive perlite. Perlite can also be used as a soilless culture substrate alone.
Peat
It comes from rotting plants in the swamp. It has strong water holding capacity, light weight after drying, and is easy to transport. The pH value of peat is usually very low, generally around 4, and it is usually mixed with lime to increase the pH to suit the growth of vegetables. Peat can be used as a substrate alone, but it is usually mixed with perlite. Peat is mainly used in North America. Because it is non-renewable, the exploitation of peat is strictly controlled in most areas on the firing boundary.
Ceramsite
Ceramsite is an inert substrate and has a neutral pH, which makes it widely used in soilless cultivation. The pores in the ceramsite can retain some water, but because the ceramsite quickly drains the water, there will be no problem of excessive glue. Before using the ceramsite, be sure to rinse it off.
Other substrates
Substrate manufacturers will introduce Xin’s cultivation substitute substrate every year. Some alternative substrates are specially manufactured, while others are by-products of other products. For beginners, the following substrates are not as good as those mentioned before, but they do not need to be purchased. Each substrate has its advantages and disadvantages. The following gives the method of how to use its advantages reasonably; due to the differences in crops and planting environments, it sometimes requires multiple experiments to get the best use of each substrate.
Gravel
The performance is similar to ceramsite.
Phenolic foam
The phenolic foam produced by “Oasis” is one of the most popular phenolic foams on the market. Phenolic foam is an excellent substitute for rock wool seedling board.
Rice husk
The performance is similar to perlite.
Cobblestone
The performance is similar to ceramsite.
Sawdust
Alternatives to peat and coconut bran, but not easy to use.
Sand
The water retention capacity is poor and heavy. The most commonly used and simplest soilless culture substrate is sand.
Bark
It is generally used in areas where wood is produced, but the source and species of the bark need to be considered.
Reuse of substrate
Cobblestone and ceramsite can be reused after cleaning, while other substrates are difficult to reuse. Most growers will mix used coconut chaff, grass charcoal and perlite into compost or directly into the soil of traditional vegetable gardens to improve the water retention and drainage of the soil. Some soilless growers also cut used rock wool blocks or rock wool boards into small pieces and mix them with the soil of traditional vegetable gardens.
Indoor cultivation equipment
Although there is no clear requirement that soilless vegetable gardens must be built indoors, most growers choose to conduct soilless cultivation indoors. Because planting indoors can reduce uncontrollable time, inject bad weather, pests and diseases, etc., but there are also some new problems when planting crops indoors. For indoor planting novices, the most common problems are poor ventilation, difficulty in controlling temperature and humidity, and insufficient light. Therefore, if you want to build a good indoor vegetable garden, you need to be equipped with corresponding equipment.
Plant growth chamber
The plant growth room is a closed space that integrates environmental control, lighting and growth systems. Sometimes it is difficult to create an environment suitable for plant growth indoors, and the ideal growth environment for plants may be different from what we think is a good living environment. The relative humidity suitable for plant growth is 50-80%, but people usually don’t like living in this humidity environment. The plant growth chamber can separate the plants from other indoor environments, ensuring that the plants have a suitable independent environment. In addition, it can also provide plants with the strong light conditions needed for growth without affecting the room environment. For example, providing 20h or longer lighting a day is beneficial to plant growth, but such a long lighting time will affect people’s rest. In addition, the plant growth room is convenient for growers to better prevent and control pests, and can spray pesticides or release beneficial insects to prevent and control diseases in a closed environment. The plant growth room is very suitable for the growers who rent a house, because the house is not owned by them, and they have no right to make renovations. Many years ago, the author blindly created a plant growth room without permission to renovate the room, and finally annoyed the landlord and lost a deposit. In order to avoid this kind of situation, the plant growth room is the best choice for gardening enthusiasts who rent houses temporarily.
Environmental regulation
According to the environment outside the plant growth room, the grower can use a fan to control the environment inside the plant growth room, and the fan can be installed inside or outside the plant growth room. The exhaust fan installed inside the plant growth chamber can remove peculiar smell, because the air exhausted by the exhaust fan in the plant growth chamber will pass through the activated carbon filter, and the activated carbon filter can absorb various odors. This device is sometimes called a negative pressure plant growth chamber. When the exhaust fan exhausts the air in the plant growth room, fresh air is sucked into the plant growth room from the pipe opening.
A near-air fan placed outside can save the limited space in the plant growth room. The air is pushed into the plant growth chamber, and the waste is forced out from the pipe port. This arrangement also becomes a positive pressure plant growth room, which can effectively prevent and control harmful organisms, because the exhausted air effectively prevents harmful organisms from entering the plant growth room. Negative pressure plant growth chambers are easier to inhale harmful organisms, but positive pressure plant growth chambers will produce outward airflow, which makes it difficult for harmful organisms to enter the plant growth chamber from places other than the air intake fan. There are many heavy-duty air intake filters to prevent insects, bacteria, fungi and pollen from entering the growth chamber.
Note: The growth lamp generates a lot of heat, and it is difficult to control the temperature only by ventilation. When using multiple high-power plant growth lights for crops, especially crops with poor heat resistance, air conditioners need to be installed to cool the crops.
Air flow
One of the most common mistakes made by novice growers in poorly ventilated rooms. Poor airflow can cause plants to appear thorny, elongated stems, weakened stems, and tip burns. It also increases the incidence of powdery mildew, but this problem is not difficult to solve. The easiest way to determine whether a plant growth room is well ventilated, carefully observe the plant leaves to see if there is any obvious shaking. Obvious swaying of the leaves indicates that there is enough airflow at the location, but there will always be “dead spots” in the plant growth chamber. Swing fan can eliminate “dead corners”.
Grow Light
The history of using artificial light sources to grow plants can be traced back to the 19th century. In the past few decades, lighting technology has made progress, and gardening enthusiasts have begun to use plant growth lights extensively. There are many kinds of plant growth lights, but not all plant growth lights are suitable for plant growth. In order to avoid loss, please read the following items carefully before buying plant growth lights.
Fluorescent lamp
It may be the most suitable plant growth lamp for novices. Compared with other plant growth lamps, fluorescent lamps are more popular and relatively cheap. Fluorescent lamps consume little power and have multiple spectrums, so growers can use fluorescent lamps to grow a variety of crops. However, fluorescent lamps may not be suitable for plants that love strong light, such as peppers. Since fluorescent lamps emit very little heat, they can be placed very close to the crops (a few centimeters away). In addition, fluorescent lamps are also suitable for growing seedlings and plants in the seedling stage.
HPS
High light intensity and low price. High-pressure sodium lamps generate a lot of heat and can heat a cold environment, but without proper ventilation or air conditioning, it is difficult to control the environment of the plant growth room. The high-pressure sodium lamp generates a lot of heat and can heat the cold environment. If there is no proper ventilation equipment or air-conditioning, it is difficult to control the environment of the plant growth room. High-pressure sodium lamps are usually used to grow fruit and vegetable crops, and can also be used to supplement light in greenhouses. The high-pressure sodium lamp is usually placed a few meters above the crop.
MH and CMH
The high-intensity fill light commonly used for plant growth can also be used as a fill light for fruit and vegetable crops. Halogen lamps emit blue light, and many growers like to work under blue light. The blue-toned light also helps prevent the plants from overgrowing. Most plant growth lamp manufacturers focus their production on more efficient ceramic halogen lamps, rather than traditional halogen lamps.
LED Grow Light
The LED has high efficiency, low power consumption, low heat production, and there are many different configurations to choose from, some are suitable for installation above the crops, and some are suitable for placement around the crops. LEDs have many different light qualities, which can significantly affect the growth of plants. Compared with LED red and blue light, LED white light has a lower effect on promoting plant growth, but growers can work comfortably under white light, while the mixed purple of red and blue LEDs is very suitable for plant growth, but growers under purple light Work will be very uncomfortable.
Other grow lights
It also includes induction lights, plasma lights, and laser lights. In addition, many other types of plant growth lights have been introduced. These trendy plant grow lights are more expensive and not suitable for beginners. Compared with traditional HPS, MH and fluorescent lamps, LED grow lights are more developed and favored by growers.
Lighting accessories
Light stand
The light stand can be hung with ropes, cables or chains, or it can be directly installed on beams or ceilings. Most indoor growers like to use rope ratchets because they can easily adjust the height of the grow lights.
Goggles
Some growers have found that working under the orange light of HPS or the purple light of LED will cause eye discomfort. The colored lenses designed for these light sources can effectively prevent these growing lights from damaging the eyes of the grower.
Pest control products and equipment
Soilless cultivation is usually carried out in a controlled environment such as a greenhouse or indoors. Even so, it is difficult for growers to completely control the occurrence of crop diseases and insect pests. Pests multiply quickly once they enter the vegetable garden. A vegetable garden with a controlled environment is very suitable for plant growth and also suitable for pest reproduction. When the insects enter the indoor vegetable garden, they are in an excellent living environment without any natural enemies, and it has almost become a paradise for insects. Although there are many ways to control pests and diseases, the best measure is prevention. Most pest control methods can be used in a controlled environment or outdoors.
Prevention method
Prevention methods include deworming techniques, such as positive pressure growth chambers and HEPA entry filters, which have been introduced in the previous indoor cultivation equipment. In addition, clean clothes should be changed before entering the indoor planting room to avoid the introduction of pests from the outside. Prevention methods also include selecting disease-resistant plant varieties, carrying out appropriate water and fertilizer management, and cultivating strong seedlings to improve their ability to resist diseases and insect pests.
Physical control
If pests and diseases have been found in the vegetable garden, then physical control can come in handy. Luis’s favorite physical method of pest control is to use a vacuum cleaner to remove pests and diseases. Other physical control methods include pulling up whole plants and using sticky insect boards, which can also be used to detect the number of pests.
Biological control
Biological control is the use of pest predators, parasites and diseases to control pest populations. The most conventional biological control method is to release ladybirds. Biological control may not be able to completely eradicate pests and diseases, but it can usually effectively control the scale of pests and diseases.
Organic pesticides
Generally, people think that organic pesticides are less toxic than conventional pesticides or chemically synthesized pesticides, but they should still be used with caution. Read the instructions on the pesticide bottle carefully to see if you need to wear gloves, goggles or respirator protective equipment. Most farms can completely control pests using only organic pesticides.
Conventional pesticides
Home gardeners rarely use conventional pesticides or synthetic pesticides (chemical synthetic pesticides). Even commercial farms that are not organically certified mostly choose to use organic pesticides, but rarely use conventional pesticides, because organic pesticides can already completely control pests and diseases. Growers need to use conventional pesticides correctly to ensure food safety.
Pest control tools
Listed below are some of the pest control tools that Luis often uses in the vegetable garden.
Vacuum cleaner
Using a vacuum cleaner to remove insects will not cause any drug residues.
Sticky Insect Board
The yellow sticky insect board is called yellow board for short, which can be used to catch and monitor aphids and whiteflies. The blue sticky insect board is referred to as the blue board, which is usually used to catch and monitor thrips.
Beneficial insects
As a natural enemy of pests, it can effectively control pests. There are many beneficial insect control options, the following are some of the most commonly used beneficial insects in home soilless vegetable gardens. However, the indoor environment of plant growth and drug residues will affect the effect of beneficial insects.
Chrysoperla carnea
Mainly used to control aphids, but also effective for controlling whiteflies and thrips.
Coccinella septempunctata
Used to control aphids.
Tenodera sinensis
Can control a variety of insects, including aphids.
Neoseiulus cucumeris
Used to control thrips and red spiders.
Amblyseius swirskii
Used to control thrips
Essential Oils
It can effectively kill or repel pests such as mites, thrips and aphids. Commonly used essential oils are allicin, clove oil, peppermint oil, thyme oil, rosemary oil and cinnamon oil.
Neem Oil
It is a natural organic pesticide that can effectively repel insects and possibly kill them.
Azadirachtin
It is an extract of Neem tree seeds. The concentrated azadirachtin is one of the most effective insecticidal compounds. The effect of azadirachtin is similar to that of essential oil. At the same time, it can also hinder the moulting process of many pests. Azadirachtin can trap pests in their larval stage and hinder their development and reproduction.
Organic Pyrethrin
Comes from chrysanthemum. As one of the most effective organic pesticides, high concentrations of organic pyrethroid can quickly kill most insects, but it may also kill beneficial insects.
Bt
It can effectively control the larvae of butterflies and moths.
Bti
A subspecies of Bt that can control fungi biologically.
Soap bar
Insecticidal soap, even after washing soap, can effectively control whiteflies and aphids.
Spinosyn
It is an organic insecticide, derived from Saccharopolysporaspinosa, which can effectively control thrips and caterpillars.
Streptomyces
A beneficial microorganism that can effectively prevent root rot and leaf fungal diseases.
Potassium Bicarbonate
A very effective inorganic fungicide that can quickly solve the powdery mildew problem and can also be used to increase the pH value of soilless cultivation systems.
Sodium bicarbonate
It is very similar to potassium bicarbonate in preventing powdery mildew. Plants can tolerate low concentrations of sodium, but when the sodium concentration is too high, plants are poisoned or suffer from nutrient deficiency symptoms. Many growers use sodium bicarbonate to control powdery mildew and other leaf fungal diseases.
Environmental parameter measurement of soilless culture
Most soilless culture systems require various instruments to detect and regulate the growth environment of plants. The instrument can measure the concentration of nutrient elements and nutrient balance, pH, temperature and light. Some measurement and monitoring tasks are carried out automatically, while others require soilless growers to make measurements on their own every day and adhere to routine maintenance.
EC
The EC meter is used to estimate the concentration of nutrient elements in the nutrient solution and is one of the very useful tools. Many companies sell EC instruments in different shapes and prices. Luis has found some low-priced but very practical EC instruments that are also very durable. Half of Luis prefer the short rod EC instrument, because the short rod EC instrument does not require calibration, is waterproof and widely used.
pH
The pH meter can effectively help the soilless growers understand the state of the nutrient solution. When judging whether nutrient deficiency occurs, the pH value is a very important reference indicator. But the pH meter is more prone to damage than the EC meter. Careful operation and maintenance work should be done, otherwise the pH meter may be quickly inaccurate or damaged. Please be careful about the description of the pH probe to ensure that the pH meter is properly calibrated and the necessary maintenance is performed regularly to maintain the accuracy of the probe. There are big differences between different pH meters on the market. Luis has tested many brands of pH meters, and currently Luis recommends the use of “Bluelab” brand pH meters.
The pH indicator solution can also test the pH value. These indicator solutions are usually used in conjunction with pH meters, including pH meter adjustment solutions that increase and decrease pH. The pH indicator solution can measure the approximate range of pH, but it is not accurate. Novice growers who are just starting soilless culture can use pH indicator solution because it is very economical and easy to use.
Light intensity
It is relatively difficult to measure the light environment, but the approximate light intensity can also be measured by the instrument to infer whether the light is sufficient.
Illuminometer
It is the most used instrument for measuring light intensity, but this instrument also has its drawbacks. The illuminance meter measures the intensity of light by simulating the process of human eyes perceiving light. But the human eye is most sensitive to green and yellow light, while plants are most sensitive to blue and red light. The light intensity measured by the illuminance meter is in lux, but lux is not applicable to plants, so people use the photosynthetic photoelectron flux density (PPFD) to describe the light intensity, and the photosynthetically active radiation (PAR) meter can measure PPFD.
PAR Meter
PAR is the acronym for photosynthetically active radiation. PAR is the photosynthetic active radiation in the visible wavelength range that plants can use for photosynthesis. PPFD is a hand letter abbreviation for photosynthetic photon flux density. PPFD is the quantity of photons per square meter (m²) in µmol per second, and the unit used is µmol/(m²·s). The PAR meter is the instrument of choice for measuring light intensity in a horticultural environment, but it is usually more expensive than an illuminance meter.
Daylight Integral (DLI) meter DLI measurement shows the light intensity transmitted per square meter per day, which is the total amount of all PPFD in a day. The unit used is mol/(m²·d). DLI does not use µmol, because the value will be very large (1 mol is 1000000 µmol).
DLI Meter
DLI measurement shows that the light intensity transmitted per square meter per day is the total amount of all PPFD in a day. The unit used is mol/(m²·d). DLI does not use µmol, because the value will be very large (1 mol is 1000000 µmol). DLI can measure the light that plants can absorb throughout the day (not only in an instant), so DLI is very practical. Since indoor light intensity does not fluctuate throughout the day like outdoors, DLI can be easily calculated indoors through a single PPFD measurement. The PPFD measurement shows the intensity of light per square meter per second. Use the following steps to convert indoor PPFD readings of 100 µmol/(m²·s) to DLI.
Multiply the PPFD by 60s to get the total light intensity per square meter per minute.
Example: 100µmol/(m²·s) x 60s = 6000µmol/(m²·min)
Multiply the number calculated in the previous step by 60min to get the light intensity per square meter per hour.
For example: 6000µmol/(m²·min) x 60min=360000µmol/(m²·h)
Multiply the number from the second step by the number of hours of light
Example: 360000µmol/(m²·h) x 20h = 7200000µmol/(m²·d)
Finally, divide by 1000000 to convert µmol to mol.
For example: 7200000µmol/(m²·d)/1000000= 7.2mol/(m²·d)
Outdoors, you can use a DLI meter to measure the DLI number. The DLI meter is used to determine the total amount of PPFD throughout the day, in mol/(m²·d).
The following table is based on Luis’s personal observations and is for reference only.
| Crop | Suitable range for DLI |
| Small leafy vegetables | 6 – 7.2mol/(m²·d) |
| Green leafy vegetables | 12 – 30mol/(m²·d)， 17 -25mol/(m²·d) in common |
| Fruits and Vegetables | 17 – 45mol/(m²·d)， 17 -25mol/(m²·d) in common |
Temperature and humidity
A simple thermometer can detect the temperature in the nutrient solution tank. The suitable water temperature for most hydroponic crops is 16-21°C. Most pH and EC instruments can also measure water temperature. Water temperature will affect EC and pH readings, so these instruments need to exclude the influence of water temperature before they can provide accurate EC and pH readings.
The thermometer and hygrometer can record the daily temperature and humidity, which is very suitable for detecting changes in temperature and humidity in a greenhouse or growth room. Growers may spend a lot of time on their plants, but they cannot stay in the greenhouse all the time. When the grower is not in the greenhouse or growing room, he can adjust the temperature and humidity according to the records of the thermo-hygrometer.
