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6.0 TROUBLESHOOTING
Problem
NO
-N Reading Low
3
NO
-N Reading High
3
No Response to
Changing Nitrate
HYDRA-DS NO
-N
3
Possible Cause
Dirty Coated electrode
Old Expired NO3 ISE
Inaccurate Potassium compensation
Ammonium Sensor has drifted
Low or No Chloride ion
Compensation
Interfering Ions Present in Sample
Bad Electrode
Bad Sensor
Remedy
Clean sensor:
Soak in 2% HCU for 5 minutes to remove algae or
rinse with weak detergent 10-15 seconds solution
to remove oils.
Soak in tap water for 30 minutes after either
cleaning method. Increase frequency of the air
blast cleaner
Perform two point calibration, the slope > 40
mV/decade if not replace NO3 Sensor
Verify Chloride ISE reading with single point
calibration.
Adjust Cl coef (see section 4.0.5)
Perform a single point calibration
Verify Cl comp is ON
Verify Chloride ISE reading with single point
calibration
Adjust Cl coef (see section 4.0.5)
Influx of interfering ions causing error, wait for ions
to clear the process, Iodide, Bromide, HS-,
Chlorate, Chlorite, Carbonate, Bicarbonate, Nitrite
Visual inspect membrane for cuts, if torn replace
electrode
Remove the electrode examine for breakage, torn
o-rings, corrosion or moisture, if any of these
issues are present:
Switch out old electrode with a new electrode,
check response, if good recalibrate the HYDRA-DS
Switch out old electrode with a new electrode,
check response, if still bad examine electrode tube
for signs of moisture.
If present remove sensor from installation and
allow the sensor to dry out. Retest with a new
electrode, if it still fails return it to the factory for
refurbishment.
Page 35
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