Some Basic Knowledge About Hydroponics

Some Basic Knowledge About Hydroponics

Factors that affect hydroponic growth include:

Hydroponics or water culture is a soilless cultivation method that allows plants to be grown using only water and a nutrient-rich solution. Here are some key points to know, especially for beginners in hydroponics:

  1. Nutrient solution preparation: First, you need to understand how to prepare the hydroponic solution. The nutrient solution typically contains all the essential elements required by plants, including primary elements such as nitrogen, phosphorus, potassium, calcium, magnesium, sulfur, as well as trace elements like iron, zinc, copper, manganese, boron, molybdenum. The solution composition may vary based on the plant type and growth stage.

  2. Lighting: Although hydroponics doesn't require soil, adequate lighting is still crucial for plant growth. Ensure that plants receive sufficient sunlight or provide appropriate artificial lighting.

  3. Oxygen supply: Oxygen availability in the water is essential for plant growth. You may need to use an air pump or other means to ensure proper oxygenation in the water.

  4. Temperature and humidity: Temperature and humidity play important roles in plant growth. Maintain suitable levels to create an optimal environment for plant development.

  5. pH and electrical conductivity: pH affects nutrient uptake, while electrical conductivity indicates the nutrient concentration in the solution. Regular monitoring and adjustment are necessary.

  6. Plant selection: Not all plants are suitable for hydroponics. Choose plants that are well-suited for this cultivation method, such as vegetables, herbs, etc.

  7. Cleanliness: Hydroponic systems require regular cleaning to prevent the growth of bacteria, mold, or algae.


In a hydroponic system, there are some important units and conversion knowledge, such as:

Nutrient solution:

kppm: ppm stands for parts per million, which represents one part in a million parts. It is a unit used to measure the concentration of a solute in a solution. For example, if we say the iron content in water is 2 ppm, it means there are 2 parts of iron in 1,000,000 parts of water.

mS/cm: mS/cm stands for millisiemens per centimeter, which is a unit used to measure the electrical conductivity of a solution. Electrical conductivity reflects the ion concentration in the solution, with higher ion concentration resulting in higher conductivity. For example, if we say the electrical conductivity of a nutrient solution is 2.0 mS/cm, it means the solution has a relatively high ion concentration.

mmol: mmol stands for millimole, which is one-thousandth of a mole (mol). A mole is the basic unit for measuring the quantity of a chemical substance. One mole of any substance contains approximately 6.02 x 10^23 basic units, such as atoms or molecules. For example, if we say a solution contains 0.5 mmol of sodium, it means that in the solution, there are 0.5 millimoles (or 0.0005 moles) of sodium ions per liter of solution.

Light Intensity: Light intensity is typically expressed in terms of Photosynthetic Photon Flux Density (PPFD), measured in micromoles per second per square meter (μmol/m²/s). This parameter describes the number of photons received per second per square meter and is an important measure of light intensity.

Temperature: In hydroponics, temperature is commonly measured in degrees Celsius (°C). Different plants have different optimal growth temperatures, and you need to adjust the temperature according to the specific requirements of the plant species you are growing.

Humidity: Humidity is typically expressed as relative humidity (RH), measured in percentage (%). Relative humidity is the ratio of the actual water vapor concentration in the air to the maximum possible concentration at a given temperature. The ideal humidity level depends on the plant species you are growing.

Water Volume: In hydroponics, it is important to measure and replace the water regularly. Water volume is typically measured in liters (L) or gallons (gal). Note that the US and UK gallons differ: 1 US gallon is approximately equal to 3.785 liters, while 1 UK gallon is approximately equal to 4.546 liters.

Weight: When preparing nutrient solutions or adjusting solution concentrations, you may need to measure the weight of solid substances. Weight is typically measured in grams (g) or milligrams (mg).

Conversion of Ion Concentrations: 1 ppm is equivalent to 1 mg/L. In some cases, you may need to convert ppm to molar concentration (M) or millimolar concentration (mM). To do this conversion, you need to know the molar mass of the solute. For example, the molar mass of nitrogen is approximately 14, so 1 ppm nitrogen is approximately equal to 0.071 mM nitrogen.

Understanding and mastering these units and conversion methods can help you accurately adjust and optimize your hydroponic system to meet the needs of your plants.


Acceptable concentration range of nutrient elements in nutrient solution

The table above provides a basic list of nutrient elements and their general acceptable concentration ranges in a hydroponic solution. Please note that these ranges can vary depending on the specific plant species and its stage of growth, so these values are for reference only.


The concentration values are mostly in ppm. If you need to convert these to mmol/L or other units, you can use the following formula:

1 mg/L (i.e., 1 ppm) = 1 mmol/L ÷ Molecular Weight

Molecular weight is the atomic weight of each element (which can be found on the periodic table) or the sum of the atomic weights of the compound.

The overall electrical conductivity (EC) of the nutrient solution should generally be in the range of 1.0-3.0 mS/cm, depending on the type of plant and its stage of growth. Please note that once the nutrient solution is added, you should use an EC meter and a pH meter to test and adjust the total ion concentration and pH of the solution.

This is a very basic table, and you can further optimize these values based on the specific plant species and stage of growth you are working with further Knowledge

Different stages of plant growth: Each stage (seed germination, seedling growth, flowering, fruiting, etc.) may have varying requirements for light, temperature, humidity, and nutrient needs.

Special requirements of different plants: Conduct detailed research on the specific plants you plan to cultivate to understand their unique needs. For instance, certain vegetables (such as lettuce) may have higher nitrogen requirements, while fruiting plants (like tomatoes) may require more potassium during the fruiting phase.

Water quality and source: Understanding your water source (including water hardness, ion content such as calcium and magnesium, pH level, potential contaminants, heavy metal content of the water,etc.) is crucial for adjusting and managing your hydroponic system effectively.

Pest and disease management: Dive deep into learning how to identify and address common diseases (such as molds, bacteria, viruses) and pests (like aphids, mites, whiteflies).

Light intensity and photoperiod: Gain knowledge about the specific light intensity and photoperiod requirements for different plant species. For example, some plants (like short-day plants) may require extended periods of darkness to initiate flowering.

Solution changing frequency: Depending on your system type and plant species, you may need to change the nutrient solution on a weekly or biweekly basis. This can have an impact on plant growth and nutrient absorption.

Solution temperature: Delve into studying the temperature requirements of different plant species concerning the nutrient solution. For instance, some tropical plants may tolerate higher solution temperatures.

At this stage,If you still passionate interest in hydroponics. These are some of the more in-depth topics involved in hydroponics, and you can further study and explore them based on your interest and needs.
Seed planting and care: This includes seed selection, seed pre-treatment (such as soaking, scarification), the appropriate environment for seed germination, and how to transplant seedlings into the hydroponic system.

Oxygen supply: In a hydroponic system, the plant roots need sufficient oxygen to grow properly. You need to learn how to provide enough oxygen in the hydroponic system, such as using an air pump and air stones for oxygen supply.

Environmental control technologies: These include the control of temperature, humidity, CO2 concentration, light, etc. If your hydroponics is conducted in a greenhouse or indoors, these environmental factors may need to be manually controlled.

Selection and setup of the hydroponic system: Different types of hydroponic systems (for example, liquid culture, nutrient solution circulation, aeroponic cultivation) are suitable for different plants and environments. You need to understand the working principle, pros and cons of each system, and how to set up and operate them.

Usage of measurement and monitoring equipment: How to use pH meters, EC meters, light intensity meters, thermo-hygrometers, etc., and understand their readings.

Plant physiology and nutrition: Understand basic physiological processes of plants, such as growth, development, photosynthesis, etc., and their demands for various nutrient elements.

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