Eureka Manta Manual Page 63 of 67
4) Rinse the sensors twice with a small quantity of your calibration standard. Discard the used
calibration standard because it is probably contaminated with DI water.
5) Immerse the sensor in the calibration standard. This is usually accomplished by securing your
Manta with the sensors pointing up, screwing the Cup onto the Manta, and filling the Cup with
your calibration standard. Make sure the standard covers the sensor entirely, and that it also
covers the thermistor for those parameters that are temperature-compensated.
6) Watch the parameter readings until they have stabilized.
7) Select the parameter to be calibrated by clicking on the Calibrations button in the Manta Manager
Home Screen, then clicking on Calibrate, and then clicking on the parameter you wish to calibrate.
For Parameters that have two calibration points, you will specify which you wish to calibrate
(usually High or Low). Enter the calibration value and click on OK. The Manta will report the
resulting Sensor Response Factor (SRF); then click on OK to accept the calibration or Quit to leave
the sensor uncalibrated. (D.5)
8) Each sensor calibration’s Sensor Response Factor (SRF) is automatically logged into the Cal Record
with the details of that calibration.
7 Can I Use Cal Solutions More Than Once?
If your QC protocol requires fresh cal solutions for every calibration, then you might as well discard
the once-used solutions. If not, then your sensitivity cost and accuracy will determine whether you
can re-use cal solutions. If, for instance, you really want your field conductivity readings to be within
1% of reading, then fresh conductivity cal solution, which is not very expensive, should be used for
each calibration. If you are not so keen on turbidity accuracy, then you can probably reuse your
turbidity cal solution once or twice because it’s pretty expensive. (D.3)
8 What standard should I use to calibrate SC? What type?
For any parameter, use a calibration standard that is near the highest reading you anticipate in the
field. For instance, if your lake usually runs about 1000 µS/cm, then calibrate with the readily available
1413 µS/cm KCl standard. Note that some sensors (not SC) have two calibration points; the second
point should be set at a convenient low point, usually zero. (D.3)
9 What is the different between calibrating % sat or milligrams per liter for DO?
Percent saturation tells you how much oxygen you have compared to how much you would have if
the water were saturated with oxygen. Milligrams per liter tells you just that: how many milligrams
of oxygen are dissolved in one liter of water. For instance, if your Manta was reading 6.0 mg/l and
the saturation tables told you that at that temperature, salinity, and barometric pressure the
saturation value was 8.0 mg/l, then your % sat would be 6/8 = 75%. You can use either measurement,
or both, but % sat is helpful during DO calibration because it should always be 100%. (D.7)
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