HM Digital Handheld Meters

Professional handheld digital meters at an unbeatable price! HM Digital Handheld Meters offer superior construction and performance to aquarium hobbyists at a very economic cost. Precision devices boast advanced microprocessor technology to ensure exceptional reliability. User-friendly features including multiple parameter measurement, easy-to-read LCD screen, auto-off function, automatic temperature compensation, factory calibration and more keeps high-tech water testing simple!

The PH-200 measures pH and temperature with superior accuracy. Waterproof pH meter is ideal for measuring pH levels in freshwater or saltwater aquariums. Handheld meter will float if accidentally released into your aquarium. Includes batteries, lanyard, pH 7.0 buffer, clear cap and storage solution. pH measurement range of 0-14 with a 0.01 resolution accurate within +/-0.02. Temperature measurement range of 32-176°F with a resolution of 0.1°F accurate within +/-2%.

Features

• Measures pH and temperature.
• Auto-ranging three point calibration with digital fine tuning.
• Waterproof housing.
• Simultaneous temperature display.
• Digital automatic calibration (one point), with digital fine tuning.
• Data-hold function and low-battery indicator.
• Replaceable Sensor (model SP-P2).
• Factory Calibrated: The PH-200 meter is three-point factory calibrated to 4, 7, and 10 pH. The meter can be recalibrated with digital calibration using the push buttons, rather than a screwdriver.

The TDS-3 measures TDS (Total Dissolved Solids) and temperature. The TDS-3 is the world's most popular TDS meter and is the most reliable and longest lasting meter of its kind. Ideal for all water purification applications, the TDS-3 is a great for measuring the quality of your reverse osmosis water to ensure pure, clean water for aquarium use. Includes a carrying case with belt clip. TDS measurement range of 0-9990 ppm with a resolution of 1 ppm accurate within +/-2%. Temperature measurement range of 32-176°F with a resolution of 0.1°F accurate within +/-2%.

Features

• Measures TDS and temperature
• Hold Function saves measurements for convenient reading and recording
• Auto-off function shuts off meter automatically after 10 minutes of non-use to conserve batteries
• Factory calibrated with a 342 ppm NaCl solution
• Meter can be recalibrated with a mini-screwdriver
• "x10" mode reads in increments only of 10 ppm (0-9990 ppm)

The COM-100 measures EC (Electrical Conductivity), TDS (Total Dissolved Solids) and temperature. Waterproof combination meter is upgraded to measure parameters in four different scales allowing for a variety of uses and greater versatility and accuracy. Handheld meter will float if accidentally released into your reverse osmosis storage container. Professional level EC/TDS meter is your choice to ensure your reverse osmosis unit is producing the purest, highest quality water for aquarium use. Includes a cap, batteries and lanyard. EC measurement range of 0-9990 µS; 0-9.99 mS with +/-2% accuracy. TDS measurement range of 0-8560 ppm (mg/L); 0-8.56 ppt with +/-2% accuracy. EC and TDS resolution to 0.1 µS/ppm. Temperature measurement range of 32-176°F with a resolution of 0.1°F accurate within +/-2%.

Features

• Measures TDS, EC and temperature.
• Four scales: µS, mS, ppm, ppt (mS and ppt are new)
• Three different non-linear EC-to-TDS conversion factors (KCl, 442TM, NaCl).
• Automatic Temperature Compensation (ATC) using three temperature coefficients.
• Waterproof housing.
• Digital Calibration (push button) to any point within the meter's range.
• Data-hold function and low-battery indicator.
• Replaceable Sensor (model SP-C1).
• Factory Calibrated: The COM-100 meter is calibrated with a 1413 µS solution. The meter can be recalibrated with digital calibration using the push buttons, rather than a screwdriver.

Specifications

Please note: While meters are automatically calibrated by the manufacturer, unavoidable jarring during shipping may affect calibration. Therefore, you should re-calibrate your tester using a Calibration Solution (sold separately) prior to initial use.

3 fl oz 1000 ppm Calibration Solution is a NaCl solution that is 1060 as KCl, 1450 as "442" and 2000 µS.

pH Buffer Packets include 3 powder packets of 4.0 pH, 6 packets of 7.0 pH, 3 packets of 10.01 pH and one empty 100 ml bottle. Each powder packet makes 100 ml of solution (when mixed with distilled or deionized water).

When not in use, rinse the pH electrode with water to minimize contamination and use pH Storage Solution (sold separately) in the protective cap. 60 cc pH Storage Solution is a specially formulated KCl solution for pH and electrodes (sensors). Combination twist-off and eyedropper style cap allow simple use.

Downloadable TDS Meter General Usage and Calibration Instructions PDF.
(Requires Adobe Acrobat Reader 4.0 or later - get it here for free)

Shop all Aquarium Controllers & Monitors.

Please click "More Information" for tips on calibration.

1. HM Digital meters come factory calibrated (at 342 PPM or 1413 µS, depending on the product) and are ready to use out of the box. They are designed to stay consistent. However, after prolonged usage, it may help to recalibrate your meter using a commercial standard NaCl-based solution (for most HM Digital meters), which is approximately, 0.5 µS of conductivity.
2. Immerse the meter into the calibration solution. If the meter does not read within 2% of the calibration solution, adjust the reading by either digital calibration (for some products) or inserting a mini screwdriver (not included) into the trimmer pot (the hole on the back of the meter). Turn the trimmer clockwise to increase the reading and counterclockwise to decrease the reading. Note that the adjuster is very sensitive. Always refer to the calibration instructions for your particular product.

Note: HM Digital products are calibrated with a 342 PPM NaCl or 1413 µS solution. This is suitable for most applications. However, if you are measuring samples that are consistently over 1000 PPM, it is recommended to recalibrate the meter for that specific application. TDS meters are more accurate when calibrated at levels that are as close as possible to the sample being tested (such as for hydroponics, aquaculture, tinting and dying or brackish water). HM Digital sells NaCl calibration solution at 342 PPM and 1000 PPM. Calibration solutions at significantly higher levels are commercially available.

For best results, always rinse the sensor pins in distilled water and allow to air dry before replacing the cap. TDS electrodes should be stored dry. (NOTE: pH and ORP electrodes must be stored in a special storage solution.)

pH Calibration
Your PH-200 has been factory calibrated to pH 7.0. While this is suitable for many applications, it is recommended to recalibrate the meter as close as possible to the pH level that will be tested, and recalibrate prior to every test will provide superior results (though this is not required). The PH-200 should be recalibrated at least once per month. If tests are conducted between wide ranges, calibration should be done more frequently. Additionally, it should be noted that the liquid pH buffer accuracy may vary.

The PH-200 features digital auto-calibration to pH 4.0, 7.0 or 10.0 and digital manual calibration to any value within the meter's range. Manual calibration can also be used as "fine-tuning." For example, if calibrating to 10.01, it is recommended to use auto-calibration to 10.00, and then manual calibration to 10.01. NOTE: If calibrating to 10 after the meter was calibrated to 4 (or vise versa), it is recommended to calibrate to 7 first, prior to calibrating to the next value. Also, if you are having trouble calibrating to 4 or 10, calibrate to 7 first, then 4 or 10.

Frequently Asked Questions Regarding the pH Meter

Q. How often should I calibrate a pH or ORP meter?
A. All pH and ORP meters need to be calibrated frequently. For best results, HM Digital recommends calibrating the PH-200 and ORP-200 a minimum of at least once per month. This could vary depending upon frequency and type of usage. For example, if you are testing a wide range daily, for the most accurate measurements, you should be calibrating your meter daily.

Q. How do I care for my PH-200 or ORP-200?
A. For best results, always make sure the sensor is saturated in the storage solution (included in the cap and the extra bottle). Rinse the sensor in distilled water after each use, especially if testing high TDS water and liquids other than water. For best results, store the meters standing upright to ensure full saturation. Calibrate frequently.

Q. Do the pH and ORP sensors need to be stored wet?
A. Yes. The sensors need to be stored in the proper storage solution. For best results, always make sure the sensor is saturated in the storage solution (included in the cap and the extra bottle). For best results, store the meters standing upright to ensure full saturation.

For best results, a meter should be calibrated as close as possible to what will be tested. For example, if the water you are testing is always around 150 ppm, then the meter should be calibrated as close to 150 ppm as possible.

If you are testing a range of values, the meter should be calibrated to the upper third of that range. For example, if you are testing RO water and tap water, and the RO water is approximately 0-10 ppm and the tap water is typically 400-500 ppm, the meter should be calibrated to approximately 350 ppm.

• The average tap water in the U.S. is approximately 350 ppm (though this varies widely from location to location and can be anywhere from zero to greater than 1000 ppm). Therefore, HM Digital factory calibrates our meters to 342 ppm.
• All HM Digital meters are factory calibrated. Therefore, calibration is not necessary out of the box. Typically, with proper care and normal usage, HM Digital TDS and EC meters will retain their calibration for at least a year.
• Only calibrate a meter if you are sure you need to. As a general rule of thumb, if you are unsure if you need to calibrate, you probably don't. It is always safer not to calibrate than to attempt doing so.
• Though calibrating correctly will improve results, for normal usage and ranges, the difference will not be dramatic.
• Never calibrate a meter to the air.
• Never calibrate a meter to distilled water.
• Never calibrate a meter to tap water, or any water or solution that is not certified.
• HM Digital calibration solutions have a shelf life of approximately 1 year unopened.
• Once opened, HM Digital calibration solutions have a shelf life of approximately 6 months, if properly stored and not contaminated.
• All calibration solutions should be stored in a cool place, out of the heat and sun.
• Contamination can occur if dipping a meter in water or a second calibration solution with a different value, and then dipping that meter back into the first calibration solution. The droplets from the water and other calibration solution will change the value. If testing between water and a calibration solution, always let the meter air dry or spray it with a compressed air can to avoid contamination.