Hydroponic Dissolved Oxygen

Hydroponic Dissolved Oxygen

DO for Hydro, Your Missing Link to Heavier Harvests?

Elevated hydroponic dissolved oxygen levels contribute to faster crop growth and heavier harvests of healthy plants.  Dissolved Oxygen (DO) levels can turn out to be a growing operation’s missing link to increased target yields.  A crop can only perform up to it’s most limiting factor. If lighting, nutrients, carbon dioxide, VPD, etc are all optimized and nobody has paid any attention to DO a serious gap can occur between what is possible versus what is being realized for crop health and harvest weights.


What Does Hydroponic Dissolved Oxygen Do?

Most plants prefer having aerobic (oxygen present) conditions at the roots. For hydroponic crops and especially water culture cultivation methods, roots can take in more water and nutrients when they are growing in an oxygen rich environment. Enriched hydroponic dissolved oxygen acts as a catalyst, helping to drive biological reactions at an increased rate; like a well trained athlete after their warm-up ready to perform at top level. Some of the following are common observations from real world growers who monitor and achieve elevated DO levels  when cropping:

Less Incidence of Pathogen Issues

Common foliar and root diseases are less likely to occur.  Some growers have even noted successful treatment and elimination of plant pathogens already present in a crop after managing and elevating DO levels.

Increased Water and Nutrient Uptake

Plants are able to use water and nutrients more efficiently and can use more when DO levels are increased in a healthy growing environment.  Interestingly, while nutrient uptake and growth rates are higher with elevated DO, fertilizer concentrations can be maintained lower in solution. This is largely due to improved rates of absorption and use; no need to over amplify fertilizers for maximum uptake versus more conventional cultivation practices.

Faster Cropping Times

Plants can develop faster with increased hydroponic dissolved oxygen levels–vegetative growth time can typically be cut in half to achieve the same sized plant after maturity in the bloom cycle versus more conventional indoor farming or greenhouse cultivation methods. Naturally, this increase annual harvest potential. Additionally, the window of opportunity for common crop pests is also reduced per cycle. Faster turn overs can add up to a better ROI.


How Much Dissolved Oxygen for Hydroponics?

Most crops being commonly being grown in water culture systems like RDWC like elevated levels of dissolved oxygen.  Common levels in a healthy water culture system usually occur at around 6 PPM (part per million).  Achieving levels of 12 PPM or greater can have a profound impact on growth rates, nutrient absorption, cropping times, plant health and yields.

A DO Meter an electronic monitor with probe that can give real time read-outs for the oxygen levels that are dissolved and circulated throughout your hydroponic system, or as delivered from a reservoir in the case of drip irrigation systems.  In some instances it can also be a controller for using technologies that increase hydroponic dissolved oxygen levels.

NOTE: there are benefits to drip irrigation growers who increase DO levels in their hydroponic reservoirs, although the results tend to be more dramatic in recirculating deep water culture systems.

A good quality DO meter is not inexpensive and as with most technologies, you often get what you pay for.  That said, measuring and monitoring the DO levels in your system is an excellent management tool and can provide a good gauge of your hydroponic system’s performance and can give you an early warning detection system before crop health begins to suffer for hydroponic root issues.

Increasing DO in Hydroponics

Good aeration and adequate flow rates through the root zone are key in keeping healthy DO levels in hydroponics. A well designed DWC or RDWC system accounts for system volume with regards to pump sizing, manifolds, tubing diameter and aeration levels. The right ratios to a specific system volume and configuration can make a difference in what is attainable for hydroponic dissolved oxygen levels.  Tools like the the Air-Reg can help take the guesswork out of the task, especially if you wish to customize your hydroponic set up.

Having the right air pump for your system can make a difference too especially when it comes to the right size and output for good aeration in the hydroponics system or reservoir. However, it is a combination of nutrient circulation and aeration that helps improve DO largely.  Bubbles do add oxygen through diffusion as they travel upwards through roots and hydroponic solutions.  It’s when a well aerated hydroponic solution is circulated in a carefully designed manner is where the magic happens–air becomes dissolved into water, thereby helping to increase DO levels. It’s important to note that elevated DO levels typically need to be maintained through continuous circulation and aeration; they don’t last long if not replenished.

Temperature and Hydroponic DO

The temperature of your nutrient solution plays a strong role in how much oxygen your solution can hold.  It is a very direct relationship.  Warmer reservoirs and nutrient delivery systems can’t hold nearly as much DO. Given that growing system surfaces tend to be warmer than is optimal for roots (typically 65 degree Fahrenheit for optimal root temperatures) managing nutrient solution temperatures with a hydroponic chiller system is also another facet in achieving elevated hydroponic dissolved oxygen levels.

Other DO Technologies

Aeration, circulation and temperature are the most common methods for increasing DO levels for improved cropping. There are other methods available to growers although they tend to be more on the experimental side or can prove to be cost prohibitive. These include dissolving bottled oxygen into solutions and using oxygen reactors.  Interestingly, some reactor technologies can increase DO levels to very high rates, for example 30+ PPM and will allow the solution to maintain the elevated levels for considerable periods in storage or while circulated through systems.

Dissolved oxygen for hydroponics- why important, tools to raise DO, tools measure DO, benefits and drawbacks