11/07/2022 | Agriculture and Farming | 8 MINUTE READ

Why Dissolved Oxygen Is Important in Hydroponic Systems

hydroponics system

If you’ve been looking to grow crops but don’t want to use traditional farming practices that rely on perfect outdoor weather and healthy soil, you should think about having a hydroponic system installed. Hydroponics is the growing of plants without soil. Any crops you want to grow in a hydroponic system are planted directly in inert growing media, after which they are supplied with oxygen, water, and nutrient-rich solutions.

When implemented properly, a hydroponic system should facilitate fast growth, high quality, and strong yields. If you decide to grow a plant in soil, the roots will be constantly searching for nutrients that will support the plant in question. By exposing the root system directly to nutrients and water, the plant won’t need to waste energy attempting to sustain itself.

All of the energy that the plant saves can then be used to grow and mature in a shorter timeline. With this solution, leaf growth and flower blooming should be enhanced. Even though every component in hydroponics is essential for the system to function correctly, new hydroponic farmers have a tendency to overlook the importance of dissolved oxygen in these systems.

Many of the nutrients that crops need to survive are only able to be absorbed if the right amount of oxygen is available. Without having access to oxygen, crops won’t grow at the normal rate and could experience deficiencies. This article takes a close look at dissolved oxygen and how it’s applied in hydroponic systems.

small hydroponics

What is Dissolved Oxygen?

Dissolved oxygen is the total amount of oxygen that’s been dissolved in water. Oxygen can get into water via rapid movement, a waste product from photosynthesis, or the atmosphere. Oxygen usually dissolves quicker in cold water as opposed to warm water. The right amount of dissolved oxygen is necessary to keep aquatic species healthy and to maintain high water quality.

If dissolved oxygen levels dip below 5.0 mg/L, the aquatic life in the body of water could experience undue amounts of stress. In the event that oxygen levels drop below 2 mg/L for a period of several hours, a large percentage of fish in the water could die. There are several different factors that determine how much oxygen is able to be dissolved in water, the primary of which is the water’s temperature. Fluctuations in temperature will affect dissolved oxygen readings.

Why is Dissolved Oxygen Important in Hydroponics, and What are its Benefits?

Dissolved oxygen is highly important for hydroponic systems and has numerous benefits for any crops you grow. For one, dissolved oxygen provides plants with the ability to convert CO2 over to energy during the photosynthesis process.

Dissolved oxygen also stops the formation and development of harmful fungi and bacteria, which are known to cause diseases like root rot. Keep in mind that dissolved oxygen can increase nutrient intake with plant roots.

An essential aspect of the photosynthesis process is plant respiration. While all plants have a certain amount of oxygen that flows through them, the plant circulators are unable to distribute oxygen in the same way as humans do. In this scenario, plants are required to obtain oxygen through their roots, which is then released onto the leaves.

The importance of dissolved oxygen also depends on the type of hydroponic system you use. If you opt for an NFT system, the lowermost portion of the root system will need to be situated in a very thin film of your nutrient solution.

The roots will then absorb nutrients as the solution flows below. However, these roots are unable to survive if the water doesn’t contain enough dissolved oxygen. Without high DO concentrations, the feeder roots will effectively suffocate, which means that the plant would likely be unable to survive.

Warmer solutions hold lower amounts of oxygen than cooler solutions. Once the nutrient solution reaches a temperature that’s higher than 81 degrees Fahrenheit, it becomes very difficult for the water to hold dissolved oxygen.

If you use a drip fertigation system, these systems need to be fed regularly while plants are grown in a sizable media buffer. While oxygen depletion is an issue with NFT systems as a result of how thin the solution is, this problem can still affect drip fertigation systems in the event that the system is poorly designed. It’s possible to maximize availability of dissolved oxygen in one of these systems with:

  • An air compressor or air blower
  • A cycle timer controller
  • The right growing media
dissolved oxygen

Do You Need to Oxygenate the Water in Hydroponics?

If you want the nutrient solution in your hydroponic system to have enough dissolved oxygen, you’ll need to oxygenate the water.

How Do Roots Get Oxygen in Hydroponic?

Regardless of the types of crops you plant in your hydroponic system, the roots of these plants receive oxygen from the nutrient-rich solution that’s placed inside. This solution mainly consists of water. Dissolved oxygen is regularly produced via processes like circulation and aeration. When it comes to hydroponics, the water should have enough dissolved oxygen to provide the roots of plants with optimal oxygenation and growth.

What to Do if Your Plants Aren’t Getting Enough Oxygen

If the crops in your hydroponic system aren’t receiving enough oxygen, it’s possible that you’ll need to boost the amount of aeration you perform. You can also increase the water’s circulation. Both of these techniques should cause dissolved oxygen levels to instantly increase. Adding extra plants to the hydroponic system should also cause oxygen levels to rise.

plants don't get enough oxygen

How To Oxygenate Plant Roots or Increase the Oxygen Level in the Hydroponic System?

There are numerous techniques that can be used to oxygenate plant roots or increase current oxygen levels in your hydroponic system, which include everything from an air pump to an oxygen gap. Consider testing out several of these techniques to determine which one is right for you and your hydroponic system.

1. Air Pump and Air Stone

Air stones are available as an affordable solution for oxygenating water in your hydroponic garden. With the use of an air pump, it’s possible to push air directly into the stone, which results in the air splitting into smaller bubbles. The bubbles that are produced will oxygenate your nutrient-rich solution, which should make it easier for you to maintain the health of your plants. Air stones are available in numerous shapes and sizes to ensure that the needs of every hydroponic system are taken into account.

2. Auto Siphoning System

An auto siphoning system is likely the most effective option when you want to introduce more dissolved oxygen into your water. Once the water level in your garden bed increases, the excess water will flow into the tube before reaching your garden bed.

When the tube is filled, a vacuum is created that drains water from your garden bed. Including this device in your hydroponic system will simplify the process of draining and refilling your garden bed while also increasing the amount of circulation that occurs.

3. Air Diffuser Tube

Air diffuser tubes are commonly used to oxygenate water with hydroponic systems. These devices come with curved tubes that have enough holes to release some oxygen into the water. During this process, large bubbles develop and rise quickly without touching the plant roots. Small bubbles are also created, which are able to be situated in the water for a lengthier period of time. These bubbles help roots receive more oxygen.

4. Oxygen Gap

Oxygen gaps refer to areas in a hydroponic system that consist entirely of air. You can create these gaps by outfitting your reservoir with an overflow system, which ensures that some water drains out before reentering the system. You could also create an oxygen gap by making sure that a portion of the grow bed isn’t placed in your nutrient-rich solution. The area that’s exposed to air allows oxygen to contact the roots and improve the health of your plants.

5. Hydrogen Peroxide

When making a solution to place in your hydroponic system, you should consider using hydrogen peroxide to effectively increase oxygen levels in the solution.

6. Hanging Roots

There are pros and cons to using hanging roots with your hydroponic system. This type of root can be an issue with certain aeroponic systems since the roots are known to dry out quicker. On the other hand, this option can be effective since the roots have more direct contact with oxygen. As long as you’re able to spray down the roots regularly to keep them humid and moist, you should obtain a high growth rate with hanging roots.

Dissolved oxygen helps plants achieve and maintain a normal growth rate. Without having access to enough dissolved oxygen, plant roots could die, which mitigates the benefits of using a hydroponic system. By aerating or circulating the water in your hydroponic system, DO levels should remain high.

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Posted by Dominic O'Donnell on November 7, 2022

Sensorex is a global leader in the design and manufacture of quality sensors for water quality and process applications. The company offers more than 2000 sensor packages for pH, ORP, conductivity, dissolved oxygen, free chlorine, chlorine dioxide, UV transmittance and other specialty measurements, as well as a full line of sensor accessories and transmitters. Its expert technical support engineers solve analytical sensor challenges with custom designs and off the shelf products.

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