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Frequently asked questions

ClearWater Sensors provide high performance in situ chemical sensors for nitrate, phosphate, silicate, dissolved iron and pH.  If you are interested in other chemical parameters, please get in touch too.

The sensors work by combining cutting edge microfluidics with sensitive wet chemical analysis methods. They draw in a sample, analyse it using colourimetric wet chemistry, and compute the concentration of sample based on comparing the sample measurement to the measurement of an onboard calibration standard.  

Using sensors allows a continuous data set in remote or inaccessible or costly to reach locations without frequent visits by personnel 

Sensors can deliver data in real time every few minutes allowing users to be alerted to and record events that would be missed by manual sampling. 

Wet chemical methods offer the most sensitive and accurate method for measurement of several key water quality parameters. Unlike other technologies (such as direct UV spectroscopy, or Ion Selective Electrode) drift is minimised and can be corrected for by analysis of onboard standards, and interferences are minimal and are either well characterised or negligible in operational settings.  

Yes. We provide all the reagents you need in a replaceable cannister that attaches to the sensor. Each analyser is shipped with a full reagent canister so that it is ready to use as soon as it arrives. We supply replacement cartridges that can be swapped out in the field. We also offer a refilling service to reuse the cartridges and minimise cost and waste.  

A reagent canister typically lasts between 1000 and 2000 measurements, depending on the parameter.

All chemical waste is stored in the reagent canister,  so no chemicals are released into the environment.


Processed data can be transmitted in real time via the RS232 interface to a modem, logger or wifi capable hub. All data – including raw data – is stored onboard the analyser and can be downloaded via USB. For deployments within range of the mobile phone network, we provide an optional telemetry unit to transmit data to the cloud. 

Despite using microfluidic channels, our sensors are remarkably resilient to biofouling. They are regularly operated in coastal waters and visited only every 3-months, where the inlet filter replaced and a new canister fitted. The longest continuous deployment to date is for over one year in the Arctic.

The sample water entering the system is filtered through a 0.45 um pore-size filter membrane, meaning that no particles large enough to cause blockages are able to enter the system.

Yes –  due to the low sample volume, the rate of clogging is very low.

In highly turbid waters, the filter may have to be changed more frequently (1 to 3 months, depending on sample rate).


The analysers are normally deployed submerged, but can also be operated on the surface. Please contact us about your application.

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Do you want to make user-friendly and high-quality nutrient measurements?

Contact us now. We are keen on helping you to assess water quality in the most reliable and precise way possible.