Hanna Marine Alkalinity Checker HI-772 (dKH)

About This Product

The Hanna Instruments Marine Alkalinity Checker HI-772 (dKH) is a compact, high-precision digital colorimeter designed to accurately measure alkalinity in saltwater and reef aquariums. Featuring advanced optical measurement technology, simple one-button operation, and an easy-to-read digital display, this convenient testing instrument eliminates the guesswork associated with traditional color-matching aquarium test kits.

Maintaining stable alkalinity is essential for a healthy reef aquarium. Alkalinity helps buffer aquarium water against sudden pH fluctuations while providing the carbonate and bicarbonate ions necessary for the formation of coral calcium carbonate skeletons. Proper alkalinity management is especially important in aquariums containing rapidly growing SPS (Small Polyp Stony) and LPS (Large Polyp Stony) corals.

The Hanna HI-772 measures alkalinity directly in degrees of carbonate hardness (dKH), eliminating the need to convert readings from parts per million (ppm). With a measurement range of 0.0–20.0 dKH and a resolution of 0.1 dKH, this digital Checker provides precise numerical results that make it easier to monitor changes in reef aquarium water chemistry.

Unlike conventional liquid test kits that require users to compare subtle color changes against printed charts, the HI-772 uses a built-in LED light source and silicon photocell to electronically evaluate the reaction between the aquarium water sample and the testing reagent. This colorimetric measurement method provides consistent, easy-to-read results while reducing subjective interpretation.

The compact, handheld design makes the Marine Alkalinity Checker convenient for routine water testing, aquarium maintenance, and monitoring calcium and alkalinity supplementation systems. Its single-button interface simplifies operation, making it suitable for beginning reef hobbyists and experienced aquarists alike.

Each Checker includes the testing accessories needed to begin measuring aquarium alkalinity, including two sample cuvettes, a reagent starter kit for 25 tests, a precision dosing syringe, and an AAA battery.

Whether you’re maintaining a mixed reef aquarium, monitoring an SPS-dominated system, or fine-tuning a calcium reactor or automated dosing system, the Hanna Marine Alkalinity Checker HI-772 provides dependable digital alkalinity measurements to help maintain a stable, thriving reef environment.

Features:

• Accurate digital alkalinity measurement provides numerical results directly in degrees of carbonate hardness (dKH).
• Eliminates color-chart guesswork by electronically measuring water samples instead of relying on visual color comparisons.
• Wide 0.0–20.0 dKH measurement range accommodates typical marine aquarium conditions and a variety of testing requirements.
• High 0.1 dKH resolution allows aquarists to monitor small changes in alkalinity over time.
• Precise colorimetric testing technology uses an LED light source and silicon photocell to measure the reaction between aquarium water and reagent.
• Simple one-button operation makes routine alkalinity testing convenient and straightforward.
• Easy-to-read digital LCD displays alkalinity results clearly without manual calculations.
• Measures directly in dKH eliminates the need to convert alkalinity readings from ppm or other measurement units.
• Ideal for reef aquarium monitoring helps maintain the stable carbonate hardness levels required for healthy coral growth.
• Supports calcium and alkalinity dosing systems provides accurate measurements for adjusting supplementation schedules.
• Useful for calcium reactor monitoring helps aquarists track aquarium alkalinity when adjusting reactor output.
• Compact handheld design makes the Checker convenient to store, transport, and use during aquarium maintenance.
• Battery-powered operation eliminates the need for external electrical connections.
• Automatic shutoff after 10 minutes helps conserve battery life when the instrument is not in use.
• Starter reagents included provide enough testing solution for approximately 25 alkalinity measurements.
• Replaceable reagent supply allows continued testing using Hanna HI772-26 Marine Alkalinity Reagents.
• Compatible with calibration verification standards using the separately available HI772-11 Calibration Check Set.
• Suitable for saltwater aquariums including mixed reefs, SPS systems, LPS displays, and marine aquaculture applications.

Specifications:

• Brand: Hanna Instruments
• Product name: Marine Alkalinity Checker HC
• Model number: HI772 / HI-772
• Product type: Digital marine aquarium alkalinity colorimeter
• Measurement parameter: Total alkalinity
• Measurement unit: dKH (degrees of carbonate hardness)
• Measurement range: 0.0–20.0 dKH
• Resolution: 0.1 dKH
• Accuracy: ±0.3 dKH ±5% of reading at 77°F (25°C)
• Measurement method: Colorimetric
• Light source: LED at 610 nm
• Light detector: Silicon photocell
• Sample volume: 10ml
• Reagent volume per test: 1ml
• Display: Digital LCD
• Operation: Single-button control
• Power supply: 1 × 1.5V AAA battery
• Automatic shutoff: After 10 minutes of non-use
• Operating temperature: 32–122°F (0–50°C)
• Maximum relative humidity: 95% non-condensing
• Dimensions: 3.4″ L × 2.4″ W × 1.5″ H (86 × 61 × 37.5mm)
• Weight: 2.3 oz (64g)
• Reagent part number: HI772-26
• Reagent kit capacity: 25 tests
• Calibration check set: HI772-11 (sold separately)
• Aquarium compatibility: Saltwater and marine reef aquariums
• Manufacturer warranty: 1 year
• Recommended application: Marine alkalinity testing, reef aquarium water chemistry monitoring, and calcium/alkalinity dosing management

Package Contents:

• 1 × Hanna HI772 Marine Alkalinity Checker HC
• 2 × Sample cuvettes with caps
• 1 × Marine Alkalinity Reagent Starter Kit (25 tests)
• 1 × 1ml dosing syringe with tip
• 1 × AAA battery
• 1 × Instruction manual
• 1 × Quick start guide

Testing Instructions:

The Hanna HI-772 uses a straightforward colorimetric testing procedure that provides direct digital alkalinity readings.

1. Prepare the water sample: Fill a clean sample cuvette with 10ml of aquarium water, reaching the marked fill line.
2. Turn on the Checker: Press the operating button and wait for the instrument to display the initial measurement prompt.
3. Zero the instrument: Wipe the outside of the cuvette with a clean, lint-free cloth to remove fingerprints and moisture. Insert the cuvette into the Checker, close the lid, and press the button to establish the reference measurement.
4. Add the testing reagent: Remove the cuvette and use the supplied syringe to add 1ml of Hanna Marine Alkalinity Reagent.
5. Mix the sample: Secure the cap and gently invert the cuvette several times to mix the reagent thoroughly.
6. Measure alkalinity: Clean the outside of the cuvette, reinsert it into the Checker, and press the button to perform the measurement.
7. Read the result: The digital display shows the aquarium’s alkalinity directly in dKH.

Recommended Reef Aquarium Alkalinity:

For many established reef aquariums, an alkalinity range of approximately 7–11 dKH is commonly maintained, depending on coral species, nutrient levels, and supplementation strategy.

A target around 8–9 dKH is a common starting point for mixed reef aquariums, although the most appropriate level depends on the specific system.

Maintaining consistent alkalinity is generally more important than frequently adjusting levels to reach a particular number.

Regular testing is especially important in aquariums containing fast-growing stony corals, which can consume significant amounts of calcium and alkalinity.

Care and Maintenance Recommendations:

Always use clean, unscratched sample cuvettes to maintain measurement accuracy. Fingerprints, water droplets, salt residue, or scratches on the cuvette can interfere with optical readings.

Rinse cuvettes thoroughly with purified water after testing and allow them to dry before storage.

Store reagents according to the manufacturer’s recommendations and avoid using expired or contaminated testing solutions.

Use only compatible Hanna HI772 reagents for routine alkalinity measurements.

Periodically verify instrument performance using the optional Hanna HI772-11 Calibration Check Set.

Store the Checker in a clean, dry location away from excessive heat, moisture, and direct sunlight.

Important Product Information:

The Hanna HI-772 measures marine alkalinity directly in dKH. It is specifically designed for saltwater aquarium testing and should not be confused with freshwater alkalinity Checkers or Hanna’s marine alkalinity model that displays results in ppm.

The HI772-26 reagent refill kit is available separately and provides enough reagent for 25 additional tests.

The Checker is a testing instrument only. It does not automatically monitor aquarium water or control dosing equipment.

Recommended application: A compact, accurate digital alkalinity tester ideal for saltwater reef aquariums, coral propagation systems, marine aquaculture, and hobbyists seeking dependable dKH measurements without the guesswork of traditional color-comparison test kits.