Blister pack of the reagent refill for the nitrite NO2 test, two bottles visible, on a white background

The two reagent bottles numbered 1 and 2, the only contents of the refill

Comparator block placed on the nine-field colour chart: hardware not included in the refill

Graph of nitrite test consumption over twelve months, up to exhaustion of the fifty tests

Reagent refill for NO2 nitrite test

Name: Reagent refill for NO2 nitrite test
Brand: JBL
Price: 6.85 USD
Availability: InStock

$6.85

This refill contains the two reagent bottles for the nitrite NO2 test, numbered 1 and 2, along with an illustrated instruction leaflet, for approximately 50 tests. The chemistry and number of tests are identical to those of the original kit.

Nitrite is the parameter tested most regularly — daily during the initial fill, then weekly thereafter. You reuse the glassware, sampling syringe, and colour chart from your nitrite test, all of which last for years.

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The summary

What's in the box: 2 numbered reagent bottles (1 and 2), plus the illustrated instruction leaflet.
What it measures: nitrite NO2, the intermediate stage between ammonium and nitrate.
How many tests: around 50, the same as the full kit.
How often: one test per day for the first three weeks, then one per week.
Refill or full kit: the chemistry is identical; only the accessories differ.
What gets sent to you: a parcel weighing 0.08 kg, bottles in their original packaging.

NO2 1 and NO2 2 reagents, approximately 50 tests, for aquarium, pond and aquaponics

This two-bottle refill lets you keep monitoring nitrite, which is the parameter most frequently tested in a live system. Written as NO2, it represents the intermediate stage of the nitrogen cycle: bacteria convert the ammonium from fish waste into nitrite, which a second bacterial family then converts into nitrate. Until that second family is established, nitrite accumulates and becomes toxic to your fish. Levels rise when a new tank is first filled, after a filter failure, or following an overly thorough rinse of the filter media.

💧 How to read a measurement

You draw 5 ml of water into each of the two test tubes. One receives five drops of each reagent, while the other keeps the untreated water and serves as a colour reference. After 5 minutes, the colour is fully developed and can be compared against the colour chart, with both tubes side by side in the grey comparator block. Allow seven minutes if the room is cool, as the reaction develops more slowly below 20 degrees.

🌿 Nitrite in aquaponics

In aquaponics, your fish and plants share the same water, and the bacterial colony in the filter is the link between the two. Nitrite is the indicator of that colony's activity: as long as it remains measurable, the nitrate your plants feed on has not yet been produced. The recommended testing frequency is once a day for the first three weeks with fresh water, then once a week. A first year managed this way will use up a set of bottles by around the sixth month. Our guide to the nitrogen cycle in aquaponics covers those first three weeks in detail.

A pale colour is not a good sign

A paler colour than usual on water that has not changed points to spent reagents, not to cleaner water, the reading will then come out too low, which is the worst possible error for this parameter. Reagent 1 also carries the Danger label, with H314 and H318 for severe skin burns and serious eye damage. Hold the bottle upright with the tip pointing down, and store the kit out of reach of children.

Buying the individual bottles rather than the set

Only the reagents run out; the glassware, the syringe, the comparator block and the colour chart from your nitrite test will last for years. Only replace the full kit if the colour chart is stained or faded, or if a test tube is broken or scratched, since it is the chart that converts colour to a value. During cycling, the ammonia refill runs out at the same rate and is worth ordering at the same time.

The right time to order it is not when the bottle runs out, but when you know consumption is about to increase. Starting a new tank, bringing a pond back into service in spring, or receiving a new batch of fish each herald a run of daily measurements. A gap in monitoring will otherwise fall at precisely the moment when values can shift from one day to the next, and that is when nitrite causes damage.

📦 Contents and storage

The refill contains two child-proof reagent bottles, numbered 1 and 2, along with an illustrated instruction leaflet in French, for approximately 50 tests. No accessories are included, that is the very point of a refill. Screw the caps on firmly and store the box in a dry place, in its original packaging and away from direct light. A bottle stored this way will keep until the date printed on it, whereas a bottle left open near a heat source loses its sensitivity within a few months.

Technical specifications

What the refill contains

Contents: 2 reagent bottlesNO2 1 and NO2 2 reagents, numbered on the label, plus the illustrated multilingual instruction leaflet
Stated battery life: Approximately 50 measurementsSame volume of reagent as in the original kit
Manufacturer reference: JBL 2412400, PROAQUATEST rangeNot to be confused with reference 2412300, the full test kit with accessories. EAN code 4014162241245, printed on the blister pack.
Corresponding test: Nitrite NO2 test, ref. 2412300The refill is only for use with the glassware, the sampling syringe, the comparator block and the colour chart from this test

Measurement frequency

Frequency at start-up: 1 reading per day, 3 weeksOn a new freshwater tank. Once a week on a new marine tank.
Frequency during maintenance: 1 measurement per weekPlus one additional reading after any disease or mortality event.
Dose per measure: 5 drops of each reagentUsing 5 ml of water, in one of the two test tubes only, the other serving as a colour reference
Measurement duration: Around 7 minutesSix steps, including a 5-minute wait before the colour is fully developed.

Security and dispatch

Hazard classification: Danger, reagent 1H314 and H318 on reagent 1, H226 and H319 on reagent 2. Child-resistant caps.
Parcel weight: 0.08 kgOriginal blister pack, shipped as is. Store dry at ambient temperature, in its packaging

To budget for separately

Both test tubes: Those from the nitrite testOne holds the treated sample, the other serves as the colour reference: you need two, not one.
Comparator block and colour chart: Those from the nitrite testThe grey block holds both tubes side by side in front of the colour chart — the only way to read the shade accurately.

4 further specifications are available in the detailed view.

In the box

2 reagent bottles with child-safety caps, numbered 1 and 2
1 illustrated multilingual instruction leaflet, French included

Reference, EAN code, note that reagents are supplied without accessories, number of tests, doses and measurement frequencies taken from the manufacturer's official data sheet and French-language instructions on 07/09/2026. Reading range and colour chart description taken on the same day from reseller product listings.

Restock the reagents, or replace the test kit?

Both kits contain the same chemistry and give the same number of tests. What separates them is the accessories included, and therefore what you already own.

Two bottles alone are not enough for a reading The nitrite reading relies on the grey comparator block, the nine-field colour chart and the graduated test tube. The refill assumes all three components are in working order.

	Reagent bottles (bottles)	Possible measurements (measurements)	Illustrated instructions	Glass test tubes with screw caps	Sampling syringe	Grey comparison block	Nine-field colour reading chart	Price
Recommended Reagent refill for NO2 nitrite testYour choice	2 bottles	50 measurements	Yes	No	No	No	No	$6.85
Nitrite TestYour choice	2 bottles	50 measurements	Yes	Yes	Yes	Yes	Yes	$15.57

Reagent refill for NO2 nitrite testRecommended

What gets depleted

Reagent bottles (bottles)2 bottles

Possible measurements (measurements)50 measurements

Illustrated instructionsYes

What lasts for years

Glass test tubes with screw capsNo

Sampling syringeNo

Grey comparison blockNo

Nine-field colour reading chartNo

Budget

Nitrite Test

What gets depleted

Reagent bottles (bottles)2 bottles

Possible measurements (measurements)50 measurements

Illustrated instructionsYes

What lasts for years

Glass test tubes with screw capsYes

Sampling syringeYes

Grey comparison blockYes

Nine-field colour reading chartYes

Budget

Contents of both columns taken from the manufacturer's official data sheet and product leaflet on 07/09/2026.

Documents & manuals

Official manufacturer's instructions, in French

Six-step protocol, order of the two reagents, number of drops, and storage instructions. This is the instruction leaflet for the complete test: it applies equally to the refill, which contains the same reagents.

PDF · 3,1 Mo

Download

Estimate your
delivery time

Parcel weight 0.08 kg, dispatched to a collection point or to your home address, chosen at checkout. Both bottles are sent in their original blister pack, which carries the EAN code and batch number. The exact shipping cost is shown in the basket.

Frequently asked questions

6 questions

6 key questions

How long does a nitrite refill last?

50tests per refill

26 wks.first year, cycling monitored day by day

47 wks.established tank, one test per week

The calculation is based on the recommended schedule: one test per day for the first three weeks of a new freshwater setup, that's 21 tests, then one per week, plus two tests after each new fish introduction. A first year run this way uses up all 50 tests around the sixth month. An established tank, tested once a week with a few extra tests after an incident, will last just under a year.

Do you go through nitrite reagent more quickly than the others?

Yes, and that is the one genuinely distinctive feature of this refill. Consumption rates vary considerably from one parameter to another.

Parameter	Actual frequency	Repurchase
Nitrite NO2	Daily at start-up, then weekly without interruption	Regular
Ammonium NH4	In bursts: once at start-up, then nothing for months	Irregular
Copper Cu	Once after a treatment, sometimes never again	Rare

Nitrite is the only one of the three for which the recommended testing frequency never stops.

Why two bottles, and what does each one do?

Because the colouring process takes place in two stages, and both reagents are added in the same order with each measurement.

Take reagent 1 and add 5 drops to the test tube containing the sample — never to the reference tube.
Take reagent 2 and add 5 drops immediately after, to the same test tube.
Swirl gently after each addition, then leave to stand for 5 minutes.

Both bottles are therefore used up at the same rate, and the refill replaces them together.

How many drops are needed per test?

Does an aged reagent affect the reading?

A tired reagent produces a paler colour, and therefore a falsely low reading. The risk is not a false alarm — it is a false sense of security.

The check takes no more than a minute: measure a sample whose condition you already know — for example, right after a significant water change on a healthy tank — and compare it with the result you obtained last time. A noticeably weaker colour than expected on water that has not changed points to the reagents, not the tank.

What precautions should be taken with these two bottles?

Reagent 1 is classified as Danger, with hazard statements H314 and H318: severe skin burns and eye damage. If it splashes into an eye, rinse immediately and thoroughly with the eyelid held open.

Reagent 2 carries statements H226 and H319 — flammable liquid and eye irritation: keep the box away from any naked flame. Both caps are child-resistant and must be screwed back on fully; a bottle lying on its side on a shelf will eventually seep along the dropper. Store the box in a dry place, at room temperature, in its original packaging.

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Reagent refill for NO2 nitrite test

The summary