v.1.0-04/26
CD50
Nutrient EC/TDS Indicator for Hydroponics and
Water Quality Testing
USER MANUAL
2
INTRODUCTION
Thank you for choosing the Triplett CD50 Nutrient EC/TDS Indicator for your
hydroponics and water quality needs. We appreciate your purchase and are
confident this reliable instrument will support accurate monitoring of your nutrient
solutions, with precise EC and TDS measurements across a wide range. Designed
with a durable graphite sensor, automatic temperature compensation, and a
waterproof (IP67) housing, the CD50 is built to deliver consistent performance in
both field and laboratory settings. We’re glad to be a part of your growing success.
Please read this manual carefully before operation to ensure safe use and optimal
performance.
What’s in the box:
• CD50 EC/TDS Meter
• (3) 1.5V AA Batteries
• Wrist Strap
• User Manual
Stay updated:
For the most recent version of this user manual, visit www.triplett.com
and search for “CD50”. You can also find the latest specifications,
FAQs, and product datasheets on our website.
PRODUCT DESCRIPTION
The product supports two power supply methods: Power adapter and PoE.
1. Sensor with Sensor Guard installed
2. Scale
3. LED Indicators
4. O-Ring
5. Battery Cap
SENSOR GUARD INSTALLATION
1. To detach the sensor guard, twist counterclockwise until completely loose and
then remove from the sensor.
2. To attach the sensor guard back on, twist clockwise until it is secured in place.
3
CF/ED/TDS SCALE
When the sensor is immersed in a solution, the LED indicator will light up and move
in between scale ranges. Once it stabilizes, it will stop at a range indicating the
CF/EC/TDS measurement.
CF EC
LED
Indicator
ppm 500
(TDS)
ppm 700
(EC×700)
2
0.2
¡
100
140
4
0.4
¡
200
280
6
0.6
¡
300
420
8
0.8
¡
400
560
10
1.0
¡
500
700
12
1.2
¡
600
840
14
1.4
¡
700
980
16
1.6
¡
800
1120
18
1.8
¡
900
1260
20
2.0
¡
1000
1400
22
2.2
¡
1100
1540
24
2.4
¡
1200
1680
26
2.6
¡
1300
1820
28
2.8
¡
1400
1960
30
3.0
¡
1500
2100
32
3.2
¡
1600
2240
34
3.4
¡
1700
2380
36
3.6
¡
1800
2520
38
3.8
¡
1900
2660
40
4.0
¡
2000
2800
45
4.5
¡
2250
3150
50
5.0
¡
2500
3500
55
5.5
¡
2750
3850
60
6.0
¡
3000
4200
4
BATTERY INSTALLATION
1. Open the battery cap following the “OPEN” marking
2. Insert three (3) AA alkaline batteries with the positive (+) end facing down
3. Reinstall the cap, ensuring the O-ring is properly seated to maintain IP67 seal
4. After installation, the LED indicators will briefly illuminate to confirm proper
powerup
NOTE:
• Use alkaline batteries only (do not use rechargeable batteries)
• Do not mix old and new batteries or different brands
• Remove batteries if the unit is not used for more than one month
• Check for corrosion when replacing batteries
OPERATION
Measurement
1. Immerse the probe into the test solution for a few seconds
2. The LED indicator will light up and move in between the ranges until it stabilizes
3. Once stabilized, the LED indicator stops at the measurement value
LED Reading Fluctuation
1. If the LED fluctuates between two readings, the actual reading is between the
two values (example: LED fluctuates between 8 and 10 = approximately 9).
2. To take another reading, remove the probe from the solution for a few seconds
and reinsert back into the solution
Temperature Response
1. For very hot or cold solutions, allow 1–2 minutes for the sensor to reach
temperature equilibrium. The meter will automatically power off while the
temperature will continue to reach equilibrium.
2. To reduce stabilization time, stir the solution with the sensor probe or place it in
a moving solution
3. If the meter powers off, remove the sensor from the solution and reinsert it back
to activate the measurement mode.
4. The LED indicator will light up and move between ranges. Once stabilized the
LED indicator stops at the measurement value.
5
CLEANING INSTRUCTIONS
Regular cleaning is recommended every two weeks (depending on frequency use).
1. Prepare cleaning solution:
a. Mix 40mL of lemon juice (~5% citric acid)
b. Add distilled/deionized water to a total of 100mL
2. Clean the sensor:
a. Remove the sensor guard
b. Soak the sensor for 10 to 15 minutes to remove mineral buildup
3. To remove tough debris on the sensor:
a. Gently wipe with a soft, lint-free cloth
b. Do not use abrasive cleaning materials
4. Rinse and dry:
a. Rinse thoroughly with distilled/deionized water
b. Blot dry
c. Reinstall the sensor guard after cleaning to protect the sensor
TROUBLESHOOTING
1. Meter turns off before reading is taken:
a. Remove from solution for 3 to 5 seconds
b. Reinsert and measure again
2. Meter does not light up:
a. Verify solution is within measurement range
b. Clean the probe (see Cleaning Instructions above)
c. Replace batteries
3. Low readings:
a. Clean the sensor per Cleaning Instructions above
6
SPECIFICATIONS
Measurement Specifications
Parameter
Range Resolution Accuracy
Electrical Conductivity (EC) 0.2 to 6.0mS/cm
0.1mS/cm (0.2 to 4.0)
0.25mS/cm (4.0 to 6.0)
±4% rdg ±1 digit
TDS (500ppm Scale) 100 to 3000ppm
50 ppm (100 to 2000)
125 ppm (2000 to 3000)
±4% rdg ±1 digit
TDS (700ppm Scale) 140 to 4200ppm
70 ppm (140 to 2800)
175 ppm (2800 to 4200)
±4% rdg ±1 digit
General Specifications
Feature Description
Display 24 LED indicator scale (bright blue LED light)
Measurement Modes EC, CF, and TDS (ppm)
Sensor Type Graphite electrode
Calibration Factory calibrated (no user calibration required)
ATC Automatic Temperature Compensation
ATC Range 32 to 122°F (0 to 50°C)
Ingress Protection IP67 (completely dust-tight and waterproof)
Operating Temperature 32 to 122°F (0 to 50°C)
Storage Temperature
32 to 140°F (0 to 60°C)
Operating Humidity <90% RH
Sensor Life >5 years (with proper maintenance)
Power Supply 3 × 1.5V AA alkaline batteries
Battery Life Approx. 3 years (10 measurements/day)
Dimensions 17.8″ (453mm) length × 1.2″ (30mm) diameter
Weight 8.1oz (230g)
Housing Material ABS + PC
Note:
• The accuracy specification is stated at 77°F (25°C) unless otherwise specified.
• Automatic Temperature Compensation (ATC) applies within specified range.
• ppm values based on selectable 500 and 700 scales.
7
CERTIFICATIONS
This product complies with applicable CE requirements, is RoHS compliant, and
has been tested to applicable IEC standards and IP67 rating (completely dust-tight
and waterproof).
WARRANTY
Triplett offers warranty to the original purchaser of its products. We guarantee that
our products will be free from defects in workmanship and materials for one (1) year
from the purchase date.
This warranty does not cover:
• Products purchased from unauthorized distributors.
• Items that have been repaired or altered by unauthorized individuals.
• Damage from misuse, abuse, misapplication, negligence, or accidents.
• Products with altered, defaced, or removed serial numbers.
• Accessories, including batteries.
Imagery is for reference and may be enhanced for clarity. Actual product appearance
and screen content may vary slightly. Specifications are subject to change without notice.
For the latest information, visit www.triplett.com.
Copyright © 2026 Triplett. All rights reserved.
