Box of the nitrite NO2 drop water test, on a white background

Contents of the nitrite kit: grey comparator block, two glass test tubes, syringe, two reagent bottles and colour chart

Nitrite reading: comparator block placed on the nine-field colour chart

The two reagent bottles from the nitrite test, numbered 1 and 2

Nitrite NO2 water test in drops

Name: Nitrite NO2 water test in drops
Brand: JBL
Price: 2600.0 JPY
Availability: InStock

¥2,600

¥867 × 3 with no fees Klarna.

Nitrite is, along with ammonia, one of the two toxic compounds in a new tank. It appears after the ammonium, when the first family of bacteria is already active and the second is not yet established, and it blocks the transport of oxygen in your fish's blood.

This test measures it from 0.025 to 1 mg/L after 5 minutes, across nine colour fields, in freshwater as in seawater.

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The summary

What you receive: 2 reagent bottles, 2 glass test tubes, a syringe, a grey comparator block and a colour chart.
What nitrite does: it oxidises haemoglobin and blocks oxygen transport. A fish can suffocate in perfectly oxygenated water.
The threshold that matters: 0.5 to 1 mg/L can already be fatal depending on the species, and fry are more sensitive to it than adults.
How long it takes: 7 minutes in all, including 5 minutes of waiting for the colour to develop.
How to choose: this test on its own tracks cycling day by day, and the test cases add ammonium, nitrate, pH and KH.
Two classified reagents: one corrosive, the other flammable; they colour a sample you have taken and never go into the fish's water.

Nitrite drop test, from 0.025 to 1 mg/L, read in 5 minutes, with a target of zero

This drop test measures nitrite from 0.025 to 1 mg/L in 5 minutes, for about 50 measurements, and tracks the cycling peak in aquariums, ponds and aquaponics. The FAO asks for a value close to zero. Dosing is done in the test tube, never in the fish water, and the NO2 refill reuses the same glassware.

Nitrite can be neither seen nor smelt. It always appears at the same point: a few days after the ammonium, when the bacteria that convert ammonium into nitrite have established themselves and those that convert nitrite into nitrate are not yet numerous enough. This is the nitrite spike, and it accounts for a large share of the deaths in the first 3 weeks of a new tank.

🩸 Nitrite and haemoglobin

Nitrite uses the chloride ion transporter in the gills, builds up in the plasma to as much as 60 times the concentration in the water, and then oxidises the iron in haemoglobin. This becomes methaemoglobin, which no longer binds oxygen, and the blood turns brown. Your fish can therefore gasp at the surface and die of suffocation in water saturated with oxygen, because the oxygen in the water is no longer carried to their tissues.

Because nitrite enters through the chloride transporter, dissolved chloride competes directly with it. Adding salt is therefore the one measure that protects your fish without changing the water's nitrite level at all. Relative to the value this test reads, expressed as NO2, the fish-farming rule of thumb is roughly 2.5 mg/L of chloride per mg/L of nitrite for cyprinids, and roughly 5 for salmonids, which are more sensitive. Use non-iodised salt without anti-caking agents, dissolved separately, and never in an invertebrate tank or on a system that feeds crops.

Sensitivity varies enormously from one species to another

Depending on the species, concentrations between 0.5 and 1 mg/L can already be lethal, and marine fish and fry are particularly sensitive to them. Trout, salmon and catfish are the most vulnerable; carp, tench and eels are much more tolerant. A level that a koi carp can withstand may therefore kill a trout in the same pond.

📈 How far along is your cycling

The only comfortable value is zero. Unlike nitrate, there is no acceptable range: any readable value shows that nitrification is not converting all the nitrite produced, and the first useful action is to change about half the volume, while the bacteria recolonise the filter. The actions that trigger a spike, such as fish introduced before the end of cycling or in too great a number, are described in the article on common mistakes.

Read the nitrite alongside the ammonium from the same day

If you are starting up a tank or a system, buy the ammonium test at the same time as this one. Nitrite alone does not tell you how far your cycling has progressed, whereas the two values read together do: ammonium falling while nitrite rises shows that the first family of bacteria is established. That way you will know whether you need to wait longer before introducing fish, rather than finding out from their behaviour.

Nitrite rising, ammonium falling

This is the normal sequence of a cycling. Test every day, and do not add any fish.

High ammonium and nitrite together

Cycling is in its early stages: the first family of bacteria is active, the second not yet. The same situation follows a disturbance, such as a filter rinsed under the tap or a pump that has been switched off.

Nitrite back in an established tank

This situation is never normal, and its usual causes are a population added all at once, overfeeding, a dead fish or a clogged filter.

In aquaponics

A readable value on an established system indicates that your biofilter is undersized for the fish load.

❄️ Nitrite when the water cools

In autumn, the activity of nitrifying bacteria slows down as the water temperature falls, while the fish are still being given their ration. A feed that is too rich in protein then produces more ammonium than the biofilter can convert, and the nitrite level climbs dangerously in a pond that stayed stable all summer. So switch to a winter feed containing wheat germ, lower in protein, as soon as the water cools, as explained in the article on feeding fish in winter. An aquaponic system goes through the same transition, and one reading a week is enough to follow it.

The test also works on cold water, but the colour develops more slowly there, sometimes with a considerable delay. Store the reagents at room temperature, between 20 and 25 °C, and leave your sample to rest for about 2 hours in a heated room before testing. If you get two conflicting readings at different temperatures, keep the higher one.

🧪 Two reagents to handle

The first bottle contains concentrated acetic acid, classified as corrosive to the skin and eyes; the second is an alcoholic solution, flammable and irritating to the eyes. Both are used only in the 5 ml vial, which you fill with water taken away from the tank, then empty down the sink after reading. During cycling, you will repeat this every day for several weeks: keep a fixed place for the kit, away from any flame and out of reach of children, and rinse the vial straight away so that no trace of reagent carries over into the next sample. When bottle 1 runs out, the NO2 reagent refill replaces both bottles without your having to buy the glassware again.

Technical specifications

Measuring nitrite

Parameter measured: Nitrite, expressed as NO2The intermediate between ammonium and nitrate in the nitrogen cycle
Measuring range: 0.025 to 1 mg/LThe target is zero: unlike nitrate, no readable value is comfortable
The colour chart fields: 0,01 ; 0,025 ; 0,05 ; 0,1 ; 0,2 ; 0,4 ; 0,6 ; 0,8 ; 1,0Nine values, from yellow to pink. The first field, 0.01, falls below the measuring range
Danger threshold: 0.5 to 1 mg/L depending on the speciesFry and marine fish are the most sensitive to it
Tests per kit: Around 50It is the bottle you empty first in a kit, because it is the routine test for cycling
Manufacturer's reference: JBL 2412300, PROAQUATEST rangeEAN code 4014162241238

The procedure

Water volume: 2 times 5 mlA treated sample and an untreated blank, side by side in the comparator block
The steps: Rinse, fill, dose 1, dose 2, wait, readAdd 5 drops of each reagent, shaking after each addition
Waiting time: 5 minutesFull colour development time
Total time: About 7 minutesHandling included
Reading: In the comparison blockThe grey block compensates for the water's own colour, peat included
Water types covered: Freshwater and seawaterOne test a day for 3 weeks on a new freshwater tank, one a week in seawater

Hazard labelling

Signal word: DangerReagent 1 marked Danger, reagent 2 marked Warning
Pictograms: Corrosion, flame, exclamation markGHS05 for reagent 1, GHS02 and GHS07 for reagent 2
Hazard statements: H314, H226, H319Skin and eye burns (acetic acid), flammable liquid and eye irritation (ethanol)
Precautionary statements: P101, P102, P303+P361+P353, P305+P351+P338, P501Keep the label for the doctor, out of reach of children, skin and eyes rinsed, dispose of as required by regulations
Precautions: Sink, ventilated room, out of reachKeep bottle 2 away from any flame, and close the cap after every measurement
Measured sample: Poured down the sinkIt never goes back into the tank, the aquarium or the pond

To allow for in addition

The test that goes with it: An ammonium testRead together, the two values show where your cycling stands
Reagent refills: Reagents only, ref. 2412400The glassware, the comparator block and the colour chart should be stored

12 further specifications are available in the detailed view.

In the box

2 reagent bottles with child-resistant caps
2 glass test tubes with screw caps
1 graduated sampling syringe
1 grey laboratory comparator block
1 colour chart with 9 colour fields
1 multilingual instruction leaflet, French included

Manufacturer's values (instructions, colour chart and safety data sheets). Chloride to nitrite ratios converted to NO2 from the EIFAC recommendation; aquaponic benchmarks from the FAO.

Manufacturer and product safety

Manufacturer: JBL GmbH & Co. KG
Postal address: Dieselstraße 3, 67141 Neuhofen, Allemagne
Contact: info@jbl.de
Website: www.jbl.de

Information provided under Regulation (EU) 2023/988 on general product safety.

Nitrite alone, or the whole nitrogen sequence?

Nitrite comes after ammonium and turns into nitrate. The question is whether you want to see one step of the chain or the whole chain.

The nitrite peak occurs in the middle of the cycle Nitrite rises as ammonium falls, and it can be read on its own or as part of the full NH4, NO2, NO3 sequence. What you need depends on where you are in the process.

	Parameters covered	Drop test kits included	Nitrite NO2, the most toxic stage	Ammonium NH4, the step that comes before	Nitrate NO3, the next stage	pH and KH, which govern the activity of the bacteria	Iron, phosphates, copper, silicates, oxygen	Reagent bottles (bottles)	Glass test tubes	Laboratory comparator block	Thermometer	Reagent refill sold separately	Price
Recommended Nitrite test onlyYour choice	1	1	Yes	No	No	No	No	2 bottles	2	Yes	No	Yes	¥2,600
6-in-1 Aquarium Water Testing KitYour choice	6	5	Yes	Yes	Yes	Yes	No	9 bottles	3	Yes	No	Yes	¥9,300
JBL ProAquaTest Lab water analysis case, 13 tests for aquarium and pondYour choice	12	13	Yes	Yes	Yes	Yes	Yes	23 bottles	12	Yes	Yes	Yes	¥18,100

Nitrite test onlyRecommended

The nitrogen sequence

Parameters covered1

Drop test kits included1

Nitrite NO2, the most toxic stageYes

Ammonium NH4, the step that comes beforeNo

Nitrate NO3, the next stageNo

pH and KH, which govern the activity of the bacteriaNo

Iron, phosphates, copper, silicates, oxygenNo

Equipment supplied

Reagent bottles (bottles)2 bottles

Glass test tubes2

Laboratory comparator blockYes

ThermometerNo

Budget

Reagent refill sold separatelyYes

6-in-1 Aquarium Water Testing Kit

The nitrogen sequence

Parameters covered6

Drop test kits included5

Nitrite NO2, the most toxic stageYes

Ammonium NH4, the step that comes beforeYes

Nitrate NO3, the next stageYes

pH and KH, which govern the activity of the bacteriaYes

Iron, phosphates, copper, silicates, oxygenNo

Equipment supplied

Reagent bottles (bottles)9 bottles

Glass test tubes3

Laboratory comparator blockYes

ThermometerNo

Budget

Reagent refill sold separatelyYes

JBL ProAquaTest Lab water analysis case, 13 tests for aquarium and pond

The nitrogen sequence

Parameters covered12

Drop test kits included13

Nitrite NO2, the most toxic stageYes

Ammonium NH4, the step that comes beforeYes

Nitrate NO3, the next stageYes

pH and KH, which govern the activity of the bacteriaYes

Iron, phosphates, copper, silicates, oxygenYes

Equipment supplied

Reagent bottles (bottles)23 bottles

Glass test tubes12

Laboratory comparator blockYes

ThermometerYes

Budget

Reagent refill sold separatelyYes

Kit contents taken from the data sheets of the two cases and of this test.

Documents & manuals

Official manufacturer's instructions, in French

Six-step protocol, number of drops, colour development time, mortality threshold by species, and what to do if a reading is high.

PDF · 3,1 Mo

Download

Estimate your
delivery time

Parcel weighing 0.15 kg, dispatched within 48 h by Colissimo or Chronopost to your home, as you choose during checkout. The reagents travel upright, in their original box. The exact cost is shown in your basket. Once unsealed, this product cannot be returned under the right of withdrawal (article L221-28, 5° of the French Consumer Code), for reasons of hygiene and health protection.

Frequently asked questions

6 questions

6 key questions

How long does a nitrite spike last?

My fish are gasping at the surface although the water is well oxygenated, why?

Because the problem is not the amount of oxygen but how it is carried. Nitrite oxidises the iron in haemoglobin, which turns into methaemoglobin and can no longer bind oxygen.

Your fish therefore gasp in water that is fully saturated. Increasing the aeration changes almost nothing here: you need to bring the nitrite level down, and protect the gills with chloride in the meantime.

At what level does nitrite become lethal?

How can you bring nitrite down quickly?

Change about half the volume, using water with a pH close to that of the tank.
Add chloride in the form of non-iodised salt, dissolved separately, never with invertebrates or crops present.
Stop feeding for 2 days, and remove anything that is decomposing.
Do not touch the filter: that is where the missing bacteria develop.

Salt does not lower the nitrite in the water; it only limits how much of it passes into the fish's blood.

The peak has passed, can I add my fish?

In aquaponics, should you also aim for zero?

Yes. Nitrates feed your crops and are wanted, nitrite is not: it is an intermediate that the biofilter must consume as fast as it produces it.

The FAO guide calls for a level close to zero, 1 mg/L at most, and notes problems in fish from 0.25 mg/L; for cold-water fish such as trout, its tolerance table drops below 0.1 mg/L. Always carry out the test on a separate sample, since the two reagents must never go into the fish water.

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Nitrite NO2 water test in drops

The summary