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Hanna Checker Magnesium HI783

Item #
Hanna Instruments
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In Stock

Our Marine Magnesium Checker HC (HI783) is designed to accurately and quickly determine the magnesium level in marine (saltwater) samples. The digital readout makes measurements effortless.
Range: 1,000 to 1,800 ppm Magnesium
Simple test process and procedure
Saltwater Compatible
Our Magnesium Checker HC (HI783) is the first marine magnesium test of its kind! This Checker® provides an uncomplicated, accurate, and budget-friendly way to measure magnesium in saltwater/marine environments. Color-coded syringes and straightforward testing steps ensure quick and easy measurements every time! Magnesium is vital in saltwater environments as it allows calcium and carbonate to be bioavailable for corals and invertebrates. Designed as a more accurate alternative to chemical test kits, our Marine Magnesium Checker HC (HI783) provides quick, accurate results in a few easy steps.
Features at-a-glance
Fewer steps than other chemical tests
Color-coded syringes make the magnesium test simple and effortless
Dedicated to a single parameter
Small size, big convenience
Ideal for: Saltwater Aquariums, Marine, and Aquaculture Applications
Magnesium Checker Tips & Tricks for Accurate Measurements
Measure liquids accurately by syringe by drawing up the plunger until the bottom seal of the plunger is at the desired volume mark. Do NOT raise the liquid to the mark as this will give a false high volume. An air gap between the plunger and liquid is normal. 
Always use clean, dry cuvettes and syringes/tips. Rinse with deionized (RODI) water only; never rinse with tank water. Dry the cuvettes before use to prevent dilution.
Ensure the sample does not contain any debris.
Whenever the cuvette is placed into the checker, it must be dry outside and free of fingerprints, oil and dirt.
Wipe the cuvette thoroughly with HI731318 microfiber cleaning cloth or a lint-free cloth prior to insertion.
Shaking the cuvette can generate bubbles, causing higher readings. To obtain accurate measurements, remove such bubbles by swirling or by gently tapping the cuvette.
Do not let the reacted sample stand too long after reagent has been added, as accuracy will be affected.
Discard the sample immediately after the reading has been taken or the glass might become permanently stained.
Keep the tips with their appropriate syringes during measurement. Clean the syringes and tips before storage.
HI783 Specifications
Range 1,000 to 1,800 ppm Magnesium
Resolution 5 ppm
Accuracy @ 25°C/77°F ±5% of reading @ 25 °C (77 °F)
Light Source Light Emitting Diode @ 610 nm
Light Detector Silicon photocell
Method Adaptation of the colorimetric EDTA method using calmagite indicator. The reaction between magnesium and the reagents causes a blue to violet tint in the sample.
Battery Type 1.5V AAA Alkaline
Auto-off After 10 minutes of non-use
Environment 0 to 50 °C (32 to 122 °F); max. 95% RH non-condensing Prepared sample cuvette (sample plus reagents) must be 18 to 28 °C (64 to 82 °F).*
Dimensions 86.0 x 61.0 x 37.5 mm (3.4 x 2.4 x 1.5”)
Weight 64 g (2.3 oz)
Ordering Information Each HI783 is delivered in a case with custom insert and is supplied with Marine Magnesium reagent starter kit (reagents for 25 tests), Sample cuvette and cap (2 pcs.), 1 mL graduated syringe with tip (2 pcs.), 5 mL syringe and tip with black printing (1 pc.), 5 mL syringe and tip with blue printing (1 pc.), 1.5V AAA alkaline battery (1 pc.), Instruction manual, Quick-reference guide.
Reagent Set - HI783-25 (25 tests)
Calibration Set - HI783-11
Warranty 1 year


Customer Reviews

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Great concept, but poor execution Jun 13, 2022
I ordered the magnesium checker the first day it was available to complete my “collection” of digital marine checkers. Unfortunately, the results are reading 300-400 higher than my other test kits and the results are very inconsistent. I dose my tank to between 1400-1500 ppm and the Magnesium checker is giving results of 1670 to >1800. I did some research on Reef2Reef forums and YouTube to see if I was doing something wrong and many others are having the same issue. My checker is currently in the mail back to Hanna who blames this seemingly widespread issue on user error. I even purchased a laboratory pipettor to ensure accurate measurement of reagents and it was still all over the place. Hopefully Hanna Instruments can work out the bugs because this item has great potential.