Digital Calcium Testing for Saltwater Aquariums

The Hanna Instruments HI758 Marine Calcium Checker HC gives reef keepers a fast, easy way to measure calcium without relying on color charts.

Designed specifically for saltwater aquariums, the HI758 uses a handheld digital colorimeter to measure calcium and display the result directly in ppm, making routine testing easier and more consistent.

For reef tanks with stony corals, clams, or other calcifying organisms, regular calcium testing is an important part of maintaining stable water chemistry.

Direct Digital Calcium Results

Traditional calcium test kits often require multiple titration steps and visual interpretation.

The HI758 simplifies the process by using a digital colorimeter to analyze the sample and provide a direct calcium concentration reading.

Designed for Marine Aquariums

The HI758 measures calcium from 200 to 600 ppm, covering the range commonly encountered in saltwater and reef aquariums.

With a 1 ppm resolution, it provides detailed readings for monitoring changes over time.

Why Monitor Calcium?

Calcium is a key component used by corals and other calcifying organisms to build calcium carbonate skeletons.

Regular calcium testing helps reef keepers manage dosing, two-part supplementation, kalkwasser, calcium reactors, and water-change schedules while keeping overall reef chemistry stable.

Key Features

• Digital calcium readings in ppm
• Designed specifically for saltwater aquariums
• 200 to 600 ppm measurement range
• 1 ppm resolution
• Accuracy of ±6 ppm ±5% of reading at 77°F
• One-button operation
• Compact handheld design
• Automatic shutoff
• Replaceable AAA battery
• HI758-26 replacement reagents available separately
• HI758-11 calibration check set available separately

Specifications

Model: HI758
Parameter: Calcium
Range: 200 to 600 ppm
Resolution: 1 ppm
Accuracy: ±6 ppm ±5% of reading at 77°F / 25°C
Method: Adaptation of the Zincon Method
Light Source: LED at 610 nm
Light Detector: Silicon Photocell
Battery: 1 × 1.5V AAA
Auto Shutoff: After 10 minutes of inactivity
Dimensions: 3.4" × 2.4" × 1.5"
Weight: 2.3 oz

Important Testing Note

The HI758 uses a dilution method and requires distilled or deionized water that is free of calcium during testing. Calcium present in the dilution water can cause falsely elevated results.

Following Hanna's testing procedure carefully is important for achieving accurate and repeatable readings.

What's Included

• Hanna Instruments HI758 Marine Calcium Checker HC
• 2 sample cuvettes with caps
• Marine calcium reagent starter kit for 25 tests
• 100 µL pipette
• Syringe with tip
• Plastic pipette
• AAA battery
• Instructions
• Quick Start Guide

Why Buy From Infinity and Beyond Aquatics?

Accurate testing is one of the easiest ways to make reef maintenance more predictable. Infinity and Beyond Aquatics carries trusted testing equipment for aquarists who want clear, repeatable information about their water chemistry.

The Hanna HI758 gives reef keepers a convenient digital alternative to traditional calcium test kits while helping track one of the most important parameters in a reef system.