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My Cardy sensor will not hold calibration (2300)
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Last Updated
10th of January, 2012

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These sensors wear out over time. Replace sensor. Item # 2340, or Contact Spectrum.

Cardy NO3-  Trouble Shooting

What are the correct standards?
For Soil: (AlSO4)
2336 450 ppm NO3--N (30mL)
2335L 20 ppm NO3--N (1L)
2329     Soil NO3- Kit

Tissue Sap, Water Samples, Greenhouse Soils- soiless (not mineralized) D.I.
2314 150ppm NO3-  (blue bottle)
2318  2000 ppm NO3- (blue bottle)

2338   450 ppm NO3--N (30 mL)
2339   20 ppm NO3--N (30mL)

Questions to ask
1. What are they measuring

2. What calibration standards are they using?
Refer them to pg. 7 of manual.

3. What is the age of the meter?
There is a number in the upper right hand side of the meter eg. 7040031
This meter was made in 1997.

4. How old is your sensor? 
Example of numbers on back of sensor:
:  0241
        80302 
 00035
This sensor was made in 1998

5. Have you ever replaced the sensor?
To replace a sensor, split the meter in half and slide the new sensor in.

6. How old are your standards?
Over 2 years you should replace.

7. How many samples are you doing?
150 samples or more for soil could cause the sensor to wear out.

8. Keep yellow sticker tab on right side of sensor.

9. Is the sensor being covered with the sample?

10. Are they using distilled water?

 

Problem:
Not staying calibrated.
Make sure it comes on OK
Get both solutions pH 4 (pink) and pH7  Connect the 2 dots in an egg shape with a few drops.

Problem:
Reads 76 when dry
Solution:
When the sensor is dry it could read anything since the 2 electrodes are not connected.
Problem:
Reads 7 with distilled water.
Solution: 
It should read 0-2.  rinse with distilled water again and make sure that there is not residue on the sensor.

Problem:
Need a NO3- table for Chrysanthemums
Answer:
There isn?Äôt any.  He would probably have to eyeball it to see that the plant looks healthy.

Symptom: Meter is giving no or incorrect reading

- Inspect sensor in bright light for cracks or flaws.
- Place 4.0 standard solution on sensor and attempt reading.  Bad sensors generally cannot read below 6.0.
- Recondition sensor.  Cover sensor in either standard solution and soak for several hours.  Rinse and attempt calibration.
 
Symptom: Calibration fails / Calibration light continues blinking after calibration effort

- Inspect sensor in bright light for cracks or flaws.
- Place 4.0 standard solution on sensor and attempt reading.  Bad sensors generally cannot read below 6.0.
- Test and/or replace batteries.  CR2032 3V Lithium batteries are available at most electronic retailers.
- Recondition sensor.  Cover sensor in either standard solution and soak for several hours.  Rinse and attempt calibration.

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