06 Mar 2019
Choosing a Dissolved Oxygen Sensor for Your Shrimp Pond
Written by Zach Stein

Dissolved oxygen sensors are the most critical sensors to have on your farm. Dissolved oxygen is the parameter that can change the fastest and it can have immediate and devastating impacts on your animals.

Many farms monitoring dissolved oxygen with handheld sensors today but with increased intensification and aeration, and the lowering of environmental dissolved oxygen due to warmer temperatures and decreasing water quality conditions, farms are increasingly looking for continuous sensor options.

In this post we want to explore the advantages of continuous dissolved oxygen monitoring in a shrimp pond and what options there are available.

Why Monitor Dissolved Oxygen Continuously in a Shrimp Pond

Dissolved oxygen is the most critical parameter to monitor in a shrimp pond. While the reasons can vary depending on the type of pond you are looking to monitor (extensive to hyper-intensive), the impacts of your animals being in low-dissolved oxygen scenarios even for a single hour can be extreme.

In extensive systems, especially those with slightly higher stocking densities, it is becoming increasingly important to monitor dissolved oxygen at night when the algael blooms in the pond stop producing oxygen as the sun has gone down. We know farmers who check their ponds 3x/night manually in such systems.

In semi-intensive up through hyper-intensive systems, knowing your dissolved oxygen allows you to turn on and off the aerators at the right time, maximizing your electricity/diesel costs.

Finally across all systems, it is critical to understand your dissolved oxygen to optimize feeding. Shrimp will eat in poor oxygen conditions, but they will not convert the food to growth, but protection. Similarly, they will not eat as much, so adding more food into the system can bring about an additional set of risks that can make a bad situation worse.

Is Manual Dissolved Oxygen Monitoring Good Enough?

No. The problem with relying upon manual testing is that it is fundamentally unreliable.

Imagine that it is 3am. The temptation for your staff to not walk that extra 100 meters and make up data is incredible high. Additionally, handheld meters can be very difficult to keep calibrated so that you can generate trustworthy readings. Finally, the interval in between manual checks is often longer than it can take for low dissolved oxygen to set in and have an impact.

To maximize your pond you need continuous dissolved oxygen monitoring and there are a number of sensors available on the market today.

Types of Dissolved Oxygen Sensors

  • Poleographic – These are the oldest and most affordable type of sensors. They generally cost between $150 – $300 (in the US) and can be integrated across a series of monitors. They need to be cleaned very regularly and recalibrated often. The recalibration process is quite complicated and labor intensive.  
  • Galvanic – These came about the in 1980’s and are the second most affordable type of dissolved oxygen sensors for your shrimp pond. They can cost between $300 – $700 per sensor and can also be integrated across a range of monitors. They are easier to keep clean and are relatively simple to recalibrate – it can be done in the ambient air.
  • Optical – These are the most recent and advanced type of dissolved oxygen sensor. They can last for up to one year without need recalibration and operate based upon measuring how quickly the fluorescense changes of an oxygen-sensitive dye. These are the most expensive sensors and can cost between $700 – $1,500 per sensor
  • Osmobot – The soon to be released sensor uses optical sensing in a new format that combines dissolved oxygen sensing with continuous pH and ammonia detection as well. No recalibration is needed, instead you replace the sensor cartridge when the system tells you to. Osmobot will be launching in the US in 2019.

Conclusion

While better sensor options are on the horizon, it is important for you to start looking at how you can automate dissolved oxygen monitoring on your shrimp farm and which sensors will be right for you.
Feel free to email us at sales@osmobot.com if you have further questions on this topic.