Hanna HI783 Magnesium Colorimeter Marine Checker

Hanna HI783 Magnesium Colorimeter Marine Checker

Hanna HI783 Magnesium Colorimeter Marine Checker is a compact, single-parameter digital colorimeter that measures magnesium in saltwater. It is built for reef keepers, marine biology users and aquaculture operators who need consistent, accurate magnesium readings to keep a marine system healthy. Instead of matching colours by eye, you get a clear number on a digital display.

Why Magnesium Testing Matters

Magnesium is a crucial element in saltwater. It helps keep calcium and carbonate bioavailable to corals and other invertebrates. When magnesium drifts, your calcium and alkalinity balance can follow, so regular, accurate magnesium testing is vital for a thriving reef or marine aquarium.

The HI783 Magnesium Checker HC from Hanna Instruments gives you a simple, accurate and affordable way to monitor magnesium in saltwater and marine environments. Colour-coded syringes and straightforward testing steps make each measurement quick and hassle-free. The digital readout removes the guesswork of judging colour shades by eye.

Key Benefits

• Designed for saltwater aquariums, marine biology and aquaculture applications.
• Easier to use and more accurate than conventional chemical colour-chart test kits.
• Colour-coded syringes make measuring sample and reagents simple and effortless.
• Dedicated to a single parameter, magnesium, for focused and reliable results.
• Simple one-button operation, so there are no complicated menus or settings.
• Large LCD digital readout for added convenience and easy reading.
• Auto shut-off after 10 minutes of non-use helps prevent the battery from draining.
• Compact size for easy travel and storage, ideal next to the tank or in a fish-room kit.

How to Use

• Use the colour-coded 1 mL and 5 mL syringes to measure the water sample and reagents accurately. The 5 mL syringes are marked with black and blue printing to keep them apart.
• Combine the sample and reagents in the sample cuvette. The reaction between magnesium and the reagents turns the sample a blue to violet tint.
• Make sure the prepared cuvette (sample plus reagents) is between 18 and 28 °C (64 and 82 °F) before taking a reading.
• Operate the meter with its single button and read the magnesium result directly in ppm on the LCD.
• Follow the supplied instruction manual and quick reference guide for the full step-by-step procedure.

Suitable For

• Reef and marine aquariums keeping corals and other invertebrates.
• Marine biology work and educational settings.
• Aquaculture applications that require magnesium monitoring.

Compatibility

• Calcium levels below 300 ppm or above 500 ppm interfere with the test. Readings are therefore intended for water with calcium between 300 and 500 ppm.
• Replacement reagent set: HI783-25 (25 tests).
• Calibration set: HI783-11.

Specifications

• Range: 1,000 to 1,800 ppm magnesium
• Resolution: 5 ppm
• Precision: ±5% of reading at 25 °C (77 °F)
• Light source: LED at 610 nm
• Light detector: silicon photocell
• Method: adaptation of the colorimetric EDTA method using calmagite indicator. The magnesium–reagent reaction produces a blue to violet tint.
• Interferences: calcium below 300 ppm and above 500 ppm
• Operating environment: 0 to 50 °C (32 to 122 °F), max 95% RH non-condensing
• Prepared sample cuvette temperature: 18 to 28 °C (64 to 82 °F)
• Battery type: 1 x 1.5V AAA
• Auto-off: after 10 minutes of non-use
• Dimensions: 86 x 61 x 37.5 mm (3.4 x 2.4 x 1.5")
• Weight: 64 g (2.3 oz)
• Reagent set: HI783-25 (25 tests)
• Calibration set: HI783-11

What's Included

• 1 x HI783 Marine Magnesium Checker HC
• 1 x carrying case
• 1 x sample cuvette with 2 x caps
• 1 x Marine Magnesium Starter Kit (reagents for 25 tests)
• 1 x 1 mL graduated syringe and tip
• 1 x 5 mL syringe and tip with black printing
• 1 x 5 mL syringe and tip with blue printing
• 1 x 1.5V AAA alkaline battery
• 1 x instruction manual
• 1 x quick reference guide

Terms of Sale

Please take the time to understand this test kit thoroughly and familiarise yourself with it before purchasing. Because of the unique nature of this product, returns cannot be accepted.

Frequently Asked Questions

What magnesium range does the Hanna HI783 measure?
It reads from 1,000 to 1,800 ppm magnesium with a resolution of 5 ppm and a precision of ±5% of reading at 25 °C (77 °F).

My fish room gets hot in a South African summer. Will that affect my readings?
The meter operates between 0 and 50 °C (32 and 122 °F). However, the prepared sample cuvette must be between 18 and 28 °C (64 and 82 °F) when you take the reading. On hot days, let the sample settle within that range before testing.

Does my calcium level affect the magnesium result?
Yes. Calcium below 300 ppm or above 500 ppm interferes with the test. Check that your calcium falls between 300 and 500 ppm for dependable magnesium readings.

How many tests do I get, and what do I need for refills?
The included Marine Magnesium Starter Kit contains reagents for 25 tests. The replacement reagent set is HI783-25 (25 tests), and the calibration set is HI783-11.

What battery does it use, and will it go flat if I forget to switch it off?
It runs on one 1.5V AAA battery, and an alkaline AAA is included. Auto-off switches the meter off after 10 minutes of non-use to help preserve battery life.

Can I return the checker if it isn't what I expected?
No. Due to the unique nature of this test kit, returns are not accepted. Please review the specifications and included items carefully before ordering.

When can I expect delivery?

• Gauteng (Jhb/Pta) - 1-3 working days
• Nationwide (Cpt/Dbn+) - 2-5 working days
• Outlying Areas - 3-7 working days

All orders are sent via Economy Road, typically through Fastway or Internet Express Couriers*. Estimated timeframes are not guaranteed. Once the order is collected by the courier, we have no control over third-party logistics and cannot make any time promises.

If you prefer a faster 🚀 shipping option, we also offer The Courier Guy during checkout in the dropdown selection. Please note that this option is not free, and you must choose it to use it. Please pay careful attention to the cutoff times and delivery timeframe for these options during checkout.

Enjoy the convenience of collection points and lockers! 📦

No more waiting at home or at work for your delivery. Simply choose a collection locker or pickup point and collect your order when it suits you.

Delivery times to lockers and pickup locations typically range from 2–7 working days, depending on your location.*

Search a PUDO Location Near You

Collection timeframes:

• Bob Box: Collect within 2 days of receiving your collection notification.
• PUDO Lockers: Collect within 36 hours of receiving your collection PIN or SMS notification.

If a PUDO parcel is not collected within 36 hours, it will automatically be transferred to the nearest PUDO Kiosk or Depot at no additional cost. The parcel will then be held there for approximately 2 days before being returned.

Please ensure you collect your parcel within the applicable collection period. Uncollected parcels will be returned to the sender, and additional shipping charges may apply should the order need to be resent.