Reagent refill for magnesium test

Regular price Dhs. 53.00
Regular price Sale price Dhs. 53.00
Dhs. 17.66 × 3 with no fees

These four bottles, two of which contain reagent 1, are the reagents for the magnesium test, providing approximately 60 readings. They measure magnesium alone, whereas total hardness adds it together with calcium.

The colour chart ranges from 0 to over 10 mg/L across eight fields, and the colour, which develops in 1 minute, should be read within the following 15 minutes. The two test tubes, the sampling syringe, the comparator block, and the colour chart from your kit all remain in use.

Ref. J2414300·Reagent refill
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The summary

The three reagents for the magnesium test, approximately 60 measurements, in freshwater.

Magnesium contributes to total hardness, but GH titration cannot distinguish it from calcium. These four bottles, including two of reagent 1, are the reagents for the freshwater magnesium test alone, and they measure it separately, for around 60 tests.

🕒 A measurement in three steps

Fill two 10 ml test tubes, add the three reagents to one of them, then wait 1 minute for the colour to develop. The colour then remains stable for no more than 15 minutes, and a later reading may give a different value. Prepare the colour chart and the comparison block before dosing and read immediately afterwards; if you are interrupted, repeat the measurement rather than reading a test tube that has been left standing.

Seven, three then two drops, in that order

The three reagents are not used in equal quantities: add 7 drops of reagent 1, then 3 drops of reagent 2, then 2 drops of reagent 3, mixing between each addition. One drop too many from any bottle will throw off the entire reading, so keep the instructions open until you have the sequence committed to memory.

Tap water, even very hard water, often contains too little magnesium for aquatic plants. The colour chart has eight fields, 0, 1, 2, 3, 6, 8, 10 and above 10 mg/L, with closer graduations at the lower end of the scale, and you are aiming for a level of 5 to 10 mg/L for healthy growth. This test is intended for freshwater only, as seawater contains approximately 1,000 mg/L.

Correcting magnesium with Epsom salt, gram by gram

If your reading remains below 5 mg/L, Epsom salt, a magnesium sulphate, raises the level without affecting the carbonates. One gram dissolved in 10 litres increases it by approximately 10 mg/L, so dose in small increments and retest before each new addition.

🔎 Iron or magnesium on the leaf

A magnesium deficiency shows first on older leaves, lower down the stem, as yellowing between veins that remain green, sometimes with curled leaves, because the plant redistributes this mobile element towards its new growth. An iron deficiency produces the same interveinal yellowing, but on the uppermost leaves, since iron is not redistributed. You therefore measure magnesium with these bottles and iron with the iron test before making any correction, so that the reading confirms what the position of the affected leaves suggests. The guide to identifying deficiencies in aquaponics compares the two patterns.

📋 Storage and renewal

Only reagent 2 is classified, bearing the Danger label along with hazard statements H314 and H318, as it contains sodium hydroxide. Store the stoppered bottles in a dry place at room temperature in their original packaging, and only open the second bottle of reagent 1 once the first is empty, since each test uses 7 drops of it compared to 3 and 2 for the other two. When starting out, one test per day lets you gauge your plants' consumption, then you can space out checks accordingly, meaning the 60 tests are most useful during the first few weeks.

Technical specifications

What the refill contains

Contents
4 bottles, including 2 of reagent 1Reagents 1, 2 and 3, with child-resistant caps
Measurements
Approximately 607, 3 then 2 drops per reading

Reading magnesium

The colour chart fields
0, 1, 2, 3, 6, 8, 10 and over 10Eight values in mg/L, compressed at the lower end of the scale for accurate readings at low concentrations
Target values
5 to 10 mg/LOptimum growth range for aquatic plants. Freshwater only.

Reference and safety

Manufacturer's reference
JBL 2414300, PROAQUATEST rangeNot to be confused with 2414200, which is the complete kit
Hazard classification
Danger, reagent 2H314 and H318 hazard statements, sodium hydroxide declared

To budget for separately

Glassware, syringe and block
Those from the magnesium testTwo test tubes side by side, one treated and one containing clear water, held in the grey block
What to correct with
Epsom salt, magnesium sulphate1 gram in 10 litres raises magnesium by approximately 10 mg/L

In the box

  • 4 reagent bottles, including 2 of reagent 1, with child-safety caps

Reference, EAN code, contents, protocol, number of tests and hazard statements taken from the JBL data sheet and instructions on 07/10/2026. The range of 0 to 10 mg/L and the detail of the eight fields are taken from a photograph of the colour chart supplied. Dilution: JBL FAQ.

Four bottles, or the magnesium kit?

The same three reagents and the same number of measurements appear in both, with the refill carrying a second bottle of reagent 1. The difference lies in the eight-field colour chart and the glassware that comes with it.

Eight fields, and 15 minutes to read them The colour only remains stable for a quarter of an hour, so everything must be ready and readable before you start. A faded colour chart makes readings unreliable.

Reagent bottles (bottles)Possible readings (measurements)Screw-top glass test tubesGraduated sampling syringeLaboratory comparator blockEight-field colour chartPrice
Recommended
Reagent refill for magnesium testYour choice		4 bottles60 measurementsNoNoNoNoDhs. 53.00
Magnesium water test in drops, freshwaterYour choice3 bottles60 measurementsYesYesYesYesDhs. 84.00
Reagent refill for magnesium testRecommended
What gets used up
Reagent bottles (bottles)4 bottles
Possible readings (measurements)60 measurements
What keeps well
Screw-top glass test tubesNo
Graduated sampling syringeNo
Laboratory comparator blockNo
Eight-field colour chartNo
Budget
Magnesium water test in drops, freshwater
What gets used up
Reagent bottles (bottles)3 bottles
Possible readings (measurements)60 measurements
What keeps well
Screw-top glass test tubesYes
Graduated sampling syringeYes
Laboratory comparator blockYes
Eight-field colour chartYes
Budget

Contents of both columns taken from the supplier's data sheet and instruction leaflet, on 05/09/2026.

Estimate your
delivery time

Parcel weight 0.08 kg, dispatched to a collection point or to your home address — your choice at checkout. All four bottles are sent in their original packaging. The exact shipping cost is shown in the basket.

Frequently asked questions

6 questions

6 key questions

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