CWP 24-7 Nutrient Monitor User manual

©2009 CWP Instruments 1.888.433.6867 www.cwpmeters.com
Operating Instructions for the 24-7 Nutrient Monitor
Specications for the 24-7 Nutrient Monitor
Range: 0.0-14.0 pH 0 - 9990 PPM 41°F – 95°F
Resolution: 0.1 pH 10 PPM 1° F
Accuracy: ±0.1 pH 2% FS ±2°F
Calibration: 2-points 7/4 PH 1382 PPM/2.76 EC 25°C/77°F
Power supply: DC 9v transformer (adapter’s power plug-in uses center power, outer ground)
Replacement or Repair Warranty (at the manufacturer’s discretion):
12 months for defective parts and materials from date of manufacture on the Monitor Body.
12 month warranty on the PPM electrode.
6 month warranty on the pH electrode.
Proof of purchase required. Warranty does not cover water damage, submersion in liquids or
abuse. Warranty will be void if the person calibrating the meter damages any calibration screw.
Operation of the 24-7 Nutrient Monitor
IMPORTANT INFORMATION
Remove the rubber protectors from the pH
electrode’s BNG connector before attaching it
to the 24-7 meter.
The PPM electrode uses a DIN connector. Find the guide
notch on the PPM electrode’s DIN connector match it to the
DIN connector on the 24-7 meter. This will line up the holes
and the pins for easy insertion. Insert and screw the DIN connectors together using the connec-
tor ring.
You have purchased a scientic instrument requiring a delicate touch when calibrating. Read
both calibration and troubleshooting sections to familiarize yourself with the meter’s operation
before calibrating. Be gentle; do not force the calibration screws past their stop. They are
sensitive and have less than 1 turn total travel. Hold the screwdriver between thumb and index
nger to turn the calibration screws. Take care in turning them as the screwdriver slots can be
stripped if pressure is applied to the screws after their maximum travel has been reached. The
warranty will be void if any calibration screw is stripped or damaged in any way.
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Rubber Protector Removed
Rubber Protector On
Closeup of PPM Electrode Connector

©2009 CWP Instruments 1.888.433.6867 www.cwpmeters.com
pH
pH Measurement –
Hang the pH electrode in the water or nutrient solution in such a manner that it is out of
harms way and the currents in the tank will ow by. The monitor will constantly display the pH
value of the solution.
When not in use, store the electrode in this manner. Clean the electrode with Rejuve it! elec-
trode cleaner, rinse with distilled water and blot dry with a clean cloth. Fill the plastic storage
bottle with Store it! electrode storage solution. Insert the electrode through the storage bot-
tle’s cap and tighten.
Occasionally clean the electrode with Rejuve It! electrode cleaner. This will rejuvenate the
glass bulb by safely cleaning build-up from the glass.
pH Calibration –
If this is a new meter, skip step 1. Allow the electrode’s glass bulb to sit in CWP’s brand of
electrode cleaner called Rejuve it! for 15 minutes. Using a soft toothbrush lightly scrub the
glass bulb. Gently rinse with distilled water and blot the bulb dry. Be careful as the glass bulb
is fragile. This procedure will help remove contaminates from the electrode’s surface so that a
true and proper calibration can be done.
Dip the pH electrode into a pH 7 buffer solution. Wait for the meters display to stabilize. Gently
turn the pH 7 calibration screw until the display reads pH 7.00. Do not turn calibration screw
past its stop.
Rinse the electrode with distilled water and blot it dry with a clean cloth.
Dip the electrode into a pH 4 buffer solution. Gently turn the pH 4 calibration screw until the
display reads pH 4.00. Do not turn calibration screw past its stop.
If necessary, repeat procedure 1 to 4 until the display shows the correct values. If calibration
is still not possible see the troubleshooting section. Rinse and blot the electrode dry each time
before inserting the electrode in a buffer solution.
Troubleshooting –
If the meter fails to calibrate pH properly after using the Rejuve it! cleaner on the electrode, the
pH calibration screws may need to be repositioned to center travel position before calibrating again.
To do this, gently turn each pH calibration screw counterclockwise until it stops and then back clock-
wise until it stops. This will show you the full travel of the calibration screw. Now gently turn each
calibration screw to the center or to its halfway position and start the calibration steps 2-4 again. If
this does not allow for enough calibration screw travel during calibration, gently turn each calibra-
tion screw (from full clockwise position) counterclockwise to the 1/4 position and calibrate the meter
again using steps 2-4. The starting position of the calibration screws is very important.
Note: If the meter fails to calibrate pH properly the pH electrode’s life may be over and will need re-
placed. The item number for this part is CW505.
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©2009 CWP Instruments 1.888.433.6867 www.cwpmeters.com
PPM
PPM Measurement –
Hang the PPM electrode in the water or nutrient solution in such a
manner that it is out of harms way and the currents in the tank will
ow by. The monitor will constantly display the PPM value of the solu-
tion. You must multiply the number on the display by 10 to get the
correct reading.
PPM Calibration –
Remove the electrode shield and wipe the elec-
trode with a clean cloth to remove sediment.
Rinse the electrode with distilled water and again
wipe it clean with a clean cloth to remove con-
tamination. Replace the electrode shield and
dip the electrode into CWP Instruments 1382
PPM/2.7 EC (500 PPM to 1 EC). Swish back and forth to dislodge air bubbles. When the display
stabilizes, gently adjust the PPM calibration screw to make the display read 138 PPM.
Temperature
Temperature Measurement –
Dip the PPM electrode (combination conductivity and temperature electrode) into the solution
for measuring. The monitor will display the correct temperature after 10 minutes.
Calibration –
Dip both the PPM electrode and a waterproof thermometer into a solution for 10 minutes
to determine temperature. (Waterproof thermometers can easily be found at stores selling
aquarium supplies). After the PPM electrode and thermometer have been submerged for 10
minutes, gently adjust the calibration screw on the meter to display the same temperature as
the thermometer.
Note: Since the temperature sensor is combined with the conductivity (PPM) sensor, it is normal for
the meter to measure conductivity (PPM) simultaneously when measuring temperature. Water tem-
perature and air temperature will rarely be the same. Before calibration, allow a waterproof thermom-
eter to stabilize in the solution to determine water temperature.
Placement -
Place the 24-7 meter out of direct light, sprays of water and areas of high humidity. Hang the
meter on a wall using the holes located on the back of the meter. Plug the 9 volt transformer
into a surge protected outlet.
*The latest electronic components have been incorporated into this meter and will hold calibration for
long periods of time. The monitors are all calibrated before leaving the factory.
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