The NKE Sensor CAL Aquaread Calcium Electrode is an Ion Selective Electrode (ISE). It tests for calcium in water by measuring the levels of charged calcium ions. Calcium is an alkaline-earth metal that is an important component of the cell walls of aquatic plants, and of the bones and shells of aquatic animals. Calcium ions find their way into water as it flows over rocks that contain calcium, such as limestone and gypsum. In freshwater, the concentration of calcium ions is generally in the range of 0 – 100 mg/L.

• This is a solid state sensor in that it is not gel-filled. The advantage of this kind of sensor over those offered by other manufacturers is that the sensor will not deteriorate over time so long as it's dry.
• A new, dry sensor can be stored for years without degradation. Gel-filled sensors, on the other hand, have a finite life from the point of manufacture.

• Successful calibration of an ISE is fairly complex. On its initial use, a three-point calibration is required. Generally, this is at 10ppm and 100ppm of the sensor's specific calibration solution, with the third point intended to characterise the effect of temperature on that specific sensor. The third point is a second calibration at 10ppm however, this calibration point must be at least 10 degrees colder than the initial point. This is because the measured concentration varies with temperature as well as the actual concentration of the ion.
• The good news is that once this calibration is complete, subsequent calibrations do not require the third point to be re-done making future calibrations much simpler to perform.

• An ideal ISE sensor would only allow the ion in question to be passed through the membrane. However, in practise all ion selective electrodes suffer from interference from ions which are similar in nature to the target ion. For this reason, ISE Electrodes are not recommended for use in brackish or salt water due to the high level of interfering ions.

• Installing the calcium sensor into an Aquaprobe is a very simple process. Simply unscrew the blanking plug from an appropriate aux socket, apply some silicon grease to the thread of the sensor (grease provided) and screw in the sensor. After installation full calibration is required.

NKE Aquaprobe-2000 Water Monitoring Probe

The NKE Aquaprobe-2000 Water Monitoring Probe is the smaller of our advanced portable multiparameter water monitoring probes. It comes with a range of standard sensors included, it also offers some customisation options that allow you to add even more sensors to the probe. All of our probes are constructed from tough marine grade aluminium that has been hard anodised, making it suitable for use in both fresh and salt waters

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NKE Aquaprobe-5000 Water Monitoring Probe

The NKE Aquaprobe-5000 Water Monitoring Probe is the larger of our advanced portable multiparameter water monitoring probes. It comes with a range of standard sensors included, and much like its smaller counterpart it offers more customisation options that allow you to add extra sensors to the probe. All of our probes are constructed from tough marine grade aluminium that has been hard anodised, making it suitable for use in both fresh and salt waters.

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NKE Aquaprobe-7000 Water Monitoring Probe

The NKE Aquaprobe-7000 Water Monitoring Probe is designed for long term deployment utilising a central cleaning system to keep the fitted sensors clean reducing the effects of bio-fouling common in extended deployments. The probe comes with all of our standard parameters including optical dissolved oxygen, it also features 6 user configurable auxiliary sockets allowing you to add multiple specialist sensors to the probe. The NKE Aquaprobe-7000 Water Monitoring Probe is capable of measuring up to 17 individual parameters at once.

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NKE Aquaprobe-6000 Water Monitoring Probe

The NKE Aquaprobe-6000 Water Monitoring Probe can be used for comprehensive spot monitoring as part of a package or it can be used in permanent deployments thanks to its new, much smaller self cleaning mechanism. It features a diameter of only 58mm (the same size as the AP-5000) making it our smallest self cleaning Aquaprobe to date.

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