Ammonia Marine Checker - Colorimeter - Hanna Instruments

Ammonia is one of the most consequential parameters in a marine system. Even at low concentrations, it can stress or kill fish and invertebrates, and during a cycle or after a system disruption, levels can shift quickly. The Hanna HI784 Marine Ammonia Checker HC gives you digital readouts in the 0.00–2.50 ppm range, with a resolution and repeatability that color-matching reagent kits simply cannot provide. Where a liquid test kit asks you to judge a color shade by eye, the HI784 eliminates that subjectivity entirely.

The workflow is straightforward: collect your sample, add the included reagents in sequence, place the cuvette in the meter, and read the result. A built-in timer keeps you on pace through the reaction steps so you do not have to track time manually. The device is dedicated to a single parameter, which means there is no mode-switching or configuration required — it does one thing and does it well. The compact housing fits easily in a cabinet or testing kit.

Because ammonia is volatile, Hanna recommends preparing and reading the sample cuvette immediately after collection. Delays between sampling and measurement can cause ammonia to dissipate, leading to artificially low readings. The cuvette must be clean, dry on the outside, and free of fingerprints before insertion — a microfiber cloth is recommended. Bubbles from shaking can inflate readings; swirling or gently tapping the cuvette resolves this. Following these handling steps consistently will keep results accurate across repeated tests.

The HI784 is suited for marine and reef aquariums, fish rooms, and small-scale aquaculture operations where regular, reliable ammonia data matters. Replacement reagents (HI784-25) are available separately and should be kept on hand. If you are testing frequently or maintaining multiple tanks, stocking extra reagent kits ensures you are never without the ability to run a test when it counts.