Chloramines & Nitrification Problems : Aquamonitrix Provides a Solution

Aquamonitrix® Real-Time Nitrite and Nitrate Analyser for optimising RAS operations, biofilter performance and water quality

Water quality has an impact on fish quality – toxicity associated with nitrite and excessively high levels of nitrate can impact fish health and growth.

The ability to accurately monitor nitrite (NO2-) and nitrate (NO3-) during the entire production cycle Is a major game-changer in maximising RAS control and performance.

Problems with existing nitrite and nitrate analysis.


Up to now, the use of real-time near-continuous monitoring had been stymied due to limitations associated with existing methods of nitrate and, in particular, nitrite measurement.

Grab sampling, followed by laboratory analysis, is time- consuming and requires skilled technicians, making high- frequency monitoring impractical. Data sets tend to lack sufficient temporal resolution to generate trends, and significant events are often missed. Meanwhile, handheld analysers based on colorimetry are manual and deliver poor accuracy.

First ‘fit for purpose’ nitrite and nitrate analyser for RAS aquaculture

Aquamonitrix® is the first analyser that enables users to obtain highly specific and accurate readings for both nitrate and nitrite, autonomously in real-time, at relevant limits of detection for RAS species in both fresh and fully saline (35 ppt) water environments.

In turn, these new insights enable RAS operations to

  • Ensure safe biofilter start-up and optimise ongoing performance
  • Avoid toxic nitrite poisoning
  • Improve water quality, supporting healthier, hungrier fish, leading to better feed conversion efficiency
  • Increase water recycling rates
  • Ensure compliance with water discharge limits

RAS research and demonstration facility – Ireland

The graph to the left) shows Aquamonitrix® tracking nitrite levels increasing with feeding during the day and decreasing at night as feeding stops and the biofilter completes the conversion to nitrate. The graph to the right shows nitrate accumulation time. (Red triangles show nitrite & nitrate levels in grab samples, analysed in an accredited laboratory).

Source: Irish Marine Institute

Start-up of two RAS units – Norway

The graphs below compare the start-up of two identical RAS units. Tracking of nitrite by Aquamonitrix® (top graph) shows that the second unit (as indicated by the darker blue peaks) taking longer to establish effective conversion to nitrite.

Pictured: Aquamonitrix® Real-Time Nitrite & Nitrate Analyser being deployed at the Marine Institute, Ireland (left) and UiT – The Arctic University of Norway (right).


Fully Saline RAS Monitoring – The Netherlands

The graphs below show Aquamonitrix® tracking nitrite (left) and nitrate (right) levels in an established commercial saline RAS unit. Source: Commercial RAS operators, the Netherlands.

How Aquamonitrix can deliver this superior this analytical performance

Existing real-time nitrite and nitrate analysers- based on UV, UV-LED, ISE or colorimetric methods – fail to deliver the performance required by the RAS industry.

But Aquamonitrix® is fundamentally different in the way it works.

Rather than simply relying on UV, UV-LED, ISE or colorimetric methods, Aquamonitrix combines ion chromatography (the gold standard for laboratory analysis of nitrite and nitrate) with LED detection. This provides exception sensitivity, delivering the low levels of nitrite detection required for RAS aquaculture.

As illustrated below, the chromatography separation step (based on the lower ionic attraction of the nitrite ions to the column) means the nitrite reaches the UV-LED detector first, enabling it to be measured accurately with high specificity – even when nitrate levels are also high.

Second, the column acts as ‘trap’ for air bubbles, condensation, organics and colour, all of the which can impact the performance of conventional analysers.

Thirdly, by using a matrix-eliminating eluent (sodium chloride), Aquamonitrix® can deliver excellent accuracy and precision in both fresh and saline water.

This low-cost, non-hazardous reagent also offers financial and safety benefits for RAS users.

Real-time alerts for instantaneous action

Datamonitrix (see screenshot below) is the proprietary Aquamonitrix® data management platform.

Datamonitrix allows users to access real-time nitrite and nitrate data remotely via a PC, define maximum threshold values and set up automated alters and alarms when these levels are breached, allowing for timely intervention.