Hanna Instruments HI781 Marine Nitrate Low Range Colorimeter
Protect your reef and saltwater aquarium with pinpoint nitrate accuracy. The Hanna Instruments HI781 Checker® HC is a handheld colorimeter engineered to measure low-range nitrate levels from 0.00 to 5.00 ppm (as NO3–) — far more reliably than color-matching test kits. No more squinting at color charts; get a clear digital readout every time.
Why Nitrate Control Matters in Reef Aquariums
Nitrate is a natural by-product of the nitrogen cycle. Too much promotes algae blooms and dinoflagellate outbreaks; too little starves SPS corals, causing color loss and tissue recession. The HI781 gives you the precise data you need to keep your reef thriving.
Key Features
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Measurement range: 0.00–5.00 ppm NO3– (extend to 0–50 ppm with the approved dilution procedure).
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Digital readout — eliminates visual color-matching errors.
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Built-in timer — guides you through each step so you never miss a reaction window.
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Saltwater-optimized — calibrated specifically for marine and reef aquarium water chemistry.
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More accurate than test kits — uses the Beer-Lambert colorimetric principle for lab-grade results.
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Single-parameter dedicated — no cross-interference from other parameters.
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Compact & portable — handheld design fits easily in your aquarium toolkit.
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Ideal for: reef aquariums, marine biology, and professional saltwater applications.
How It Works
Add the pre-measured HI781-25 reagent packet to your water sample. The HI781 uses the Beer-Lambert principle to detect the pink/violet color change caused by the nitrate-reagent reaction and converts it to a precise ppm reading — in minutes.
In the Box
HI781 Checker® HC colorimeter, sample cuvettes, HI781-25 reagent sachets (starter supply), instructions. Replacement reagents sold separately as HI781-25 (25 tests).
