"A technique of growing plants in nutrient solution."

Hydroponics means literally ‘water-working’ or ‘water-activation’. It’s a soiless cultivation technique; plants grow in nutrient solution rather than in soil.

The nutrient solution and its management are the cornerstone for success in hydroponics system. The function of a hydroponics nutrient solution is to supply the plants’ roots with water, oxygen and essential mineral elements in soluble form.

There are 17 mineral elements that are generally essential for growth of higher plants. Nine of these elements (macro nutrients): carbons, hydrogen,oxygen, sulphur, phosphorus, calcium, magnesium, potassium, and nitrogen are required in relatively large amounts. The remaining eight elements (micro nutrients or trace elements): iron, zinc, copper, manganese, boron, chlorine, cobalt and molybdenum are needed in only minute amounts.

Nutrient solution can be prepared using commercial available premix chemicals or from inorganic fertilizer salts.

PH and Electrical Conductivity are the two important parameters in nutrient solution control.

pH of nutrient solution
pH is a measurement of the hydrogen ion concentration in a particular medium, such as water, soil, etc. More simply, it refers to the degree of acidity and alkalinity of that medium. It is measured in a logarithmic scale ranging from 0 to 14. A pH value of 7 is neutral, a pH value below 7 is acidic and a pH value above 7 is alkaline.

The pH of a nutrient solution or a medium is important to plant growth. Every plant species has a preferred pH range in which it will grow best. If a plant is subjected to a pH outside its preferred range, retardation of growth and even death of the plant may result.

pH Adjustments
For most hydroponics cropping, the pH of the nutrient solution should not be allowed to rise above 6.5 or to fall below 6. For pH adjustments, sodium hydroxide (NOaH) is the preferred alkali and hydrochloric acid (HCI) is the preferred acid.

However, for some plants, the pH of the nutrient solution is best allowed to seek its own level naturally rather than continuously adjusted. This is because some plant species are capable of reducing the pH of the nutrient solution in the immediate vicinity of their roots. This acidification enhances their ability to absorb certain elements such as iron. If the nutrient solution is constantly adjusted, it can interfere with the plant's natural ability to enhance its absorptive capability.

Trans's Horti-Care pH Check is designed for nutrient pH test. It is rugged, water and drop-shock resistant, the ultimate pH pocket size meter.

Conductivity
The concentration of the nutrient elements in a nutrient solution can be estimated by measuring the ability of the nutrient solution to conduct an electric current. This is because the quantity of dissolved solids in the nutrient solution is directly proportional to the conductivity. When there is a greater concentration of nutrients, the current will flow faster, and when there is a lower concentration, the current will flow slower. Thus, by measuring the conductivity, one can determine how strong or weak a nutrient solution is.

Conductivity is generally measured at 25 °C. A rise in temperature or a drop in temperature will result in a corresponding rise or drop in conductivity even though no extra nutrient elements are added. It is possible to correct the conductivity data to standard temperature of 25 °C by multiplying the conductivity by a temperature conversion factor (see table below).

Table: Temperature conversion factors for correcting conductivity data to standard temperature of 25 °C

Insufficient oxygen in nutrient is the cause of root rots and other diseases. The HortiCare OxyCheck meter is designed to measure dissolved oxygen in nutrient.

Light is a necessity to plant growth. Sufficient light is needed for photosynthesis to take place so plants can flower or even bare fruit.

Houseplants have become popular as indoor decorations. Attractive and refreshing, they break the monotony of a room and bring back a little nature indoors. However, the ideal spot to locate a plant for decoration may not be ideal for plant growth. Lack of adequate light is the most common cause of plants turning yello and having poor growth. Supplementary electrical lighting is the easiest and least expensive way to provide enough light for the plants. As all artificial lighting will degrade in intensity with time, it is essential to measure with the Horti-LiteCheck tester at regular intervals to tell if replacements are required.