Hydroponics Dissolved Oxygen
In hydroponic growth systems, plants are grown in soilless media and receive all essential nutrients from a nutrient solution, including oxygen. Oxygen is required for aerobic respiration in plant root systems and to support a community of beneficial aerobic bacteria in the root zone.
There are multiple types of hydroponic systems. Some of the most common include deep water culture, where the plant roots are submerged in a nutrient solution; aeroponics systems, where the plant roots grow in air and are misted with a nutrient solution; nutrient/polymer film technique, where the very ends of roots are in contact with a surface wetted with nutrient solution; and drip or passive irrigation systems, where the plant roots grow in an inert media such as coco peat, rockwool, or perlite, and nutrient solution slowly drips through.
In hydroponic systems, oxygen is mainly supplied to the plant roots in the form of dissolved oxygen (DO) in the nutrient solution. Root growth and nutrient uptake is dependent on the concentration of dissolved oxygen. For most plants, it is recommended to maintain DO concentrations above 5 parts per million (PPM) or 5 mg/L. If the amount of oxygen present in the root zone is inadequate, plant growth will become stunted due to underdeveloped roots and limited nutrient absorption. Insufficient oxygen levels can also promote undesirable bacteria and fungi growth. It is important to regularly test DO concentrations since factors such as temperature, root respiration and oxygen consumption can reduce DO concentrations. As the water temperature increases, the solubility of oxygen decreases. To maintain DO concentrations greater than 5 ppm aeration should be provided through the use of air pumps, oxygen stones/diffusers, addition of chemicals such as hydrogen peroxide, or physically by rapid mixing.
Hanna offers a wide range of equipment and accessories to measure and monitor dissolved oxygen in hydroponic nutrient solutions.
Below are the most common products used in hydroponic dissolved oxygen measurement.
A variety of benchtop meters are available to measure dissolved oxygen. These meters include basic benchtop with segmented LCD to an advance version with a large dot matrix display that has many advance features including automatic barometric pressure compensation.
in this category are the edge meters that are tablet in design and can be used as a portable, benchtop or wall mounted meter. The edge meters are are available as a single parameter meter that measures only dissolved oxygen to a multiparameter meter that can be upgraded with probes to measure pH and for EC/TDS.
A variety of portable meters are available to measure dissolved oxygen. These meters include multiparameter versions that use multiparameter probes that can measure pH and EC/TDS in addition to dissolved oxygen.
In this category are solutions used to maintain and calibrate the dissolved oxygen probes.
Accessories include replacement membrane caps that are used with dissolved oxygen probes and magnetic stirrers used with benchtop metes to ensure adequate mixing when performing a measurement.