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mgN/L) while providing a relatively wide range (up to 10 mgN/L). In practice, this is not representative for
the performance of the instrument since two separate flow cells would be used.
4) Laboratory Testing
The ACT report states that “Instruments were set-up by the manufacturer daily prior to start of each
individual laboratory test.”. At Real Tech’s own decision, the Real Tech analyzer was not set up for each
laboratory test, but instead for the whole laboratory challenge once at the beginning. A set up performed at
the beginning of each laboratory test would have yielded better results. However, this would have been
unrealistic as real-world applications are likely to present more than one interfering factor at all times.
It is important to also note that one of the highest absolute differences for a nitrate concentration of 1 mgN/L
was observed during the concentration range test. During the range test, no interfering substance was
intended to be present in the testing tank water. Therefore, the value obtained from the range test was used
as a reference for other laboratory tests. However, all other laboratory test results for the same
concentration of 1mgN/L, with the exception of 30 PSU salinity and 10 mg/L DOC, yielded absolute
differences less than this reference value despite possible interference from the test matrix. For this reason,
we believe that the concentration range test may have been confounded by the presence of an interfering
substance in the testing tank water, despite the best efforts of the ACT team. It is possible that the
interfering substance may have affected readings of all concentrations tested during the range test.
5) Data Collection Frequency
Although data collection frequencies higher than every 15 min were not deemed an important feature for the
Challenge, we believe that in many real-world applications data collection frequencies may play a critical
role. For this reason, we would like to clarify that the accurate frequency of data readings for Real Tech’s
analyzers ranged between 2 min 34 sec and 3 min 41 sec for the Nutrient Challenge field and laboratory
tests. Moreover, data collection frequency of Real Tech’s analyzers is modifiable based on the clients’
needs and can be as high as every minute.
6) Maintenance
Real Tech’s analyzers have the capacity to alarm due to a series of potential problems that may arise and
impact the operation of the instrument. As per the Challenge’s protocol, the analyzers were not to be
serviced by the manufacturer during the Challenge as durability testing was part of the competition.
However, some of the alarms that occurred during testing could have easily been resolved by Real Tech’s
staff to ensure high accuracy data collection. Although an instrument should ideally be able to operate
without maintenance for long periods, we believe it is equally important that the instrument is intelligent
enough to inform the user of any issues that arise during deployment. This two-way communication capacity
of Real Tech’s analyzers provides an extra level of confidence for the proper operation of the instrument.
We would like to thank the ACT team again for their hard and thorough work throughout the Nutrient
Challenge. It has been an invaluable experience for Real Tech.
Sincerely,
Kerim Kollu, Ph.D.
Applications Research Scientist
Real Tech Inc.
kerim@realtechwater.com1-905-665-6888