Elos Test Kit Nitrates – NO3


We continued in our presentation of Elos’s test, after we see the dKh, Magnesium and Calcium today is the time of the one must important test of aquarium world, that both fresh and marine water, the nitrate test, or the Elos NO3 Test.

Iquitos - mangimi tropicali - Colombo

Elos Test Kit Nitrates – NO3

You can see from the photo, the test has one regular box that contain the test’s instruction, the test’s explain, one little glass test tube with Elos symbol and his plastic plug, two tube which contain the reagents, one of these with powder reagent called A and one with liquid reagent called B, one syringe and the classic Elos measuring spoon.

The reagents and the tube are contained inside a plastic bag.

Unfortunately, when they thought about the box, they did it slightly too low, so the “B” reagent bottle can’t stay standing but must be inserted horizontally.


The scale of nitrates detectable has the following values: 0 – 1 – 2,5 – 5 – 10 – 25, making it particularly useful for salt water aquarists rather than fresh water aquarists. I remember that, in a reef tank it would be better to have very low values of nitrates, close to zero, or in any case between zero and one, to have a beatiful coloration of our corals.

The test is really quite simple.

We have to fill the vial with 5 ml of aquarium water.

2014_03_elos_test_kit_021Then we have to put a spoon of the powder contained in the container named A making sure it get directly into the vial. The measuring spoon provided is really very practical.

We have to shake gently the tube for 15 seconds with closed provided cap.

Then we have to add 6 drops of reagent B and we have to gently shake the vial for 10 seconds and put the vial for 5 minutes before reading the value.

Reading is done, as usual, from the top, holding the vial on a white card reference, being careful not to make a shadow with the same vial on the card. The test is extremely simple, also the identification of the color is rather simple.

The next picture is the reference cardboard to download, to verify the correspondence of color, even if because of the print it may differ from the original.


The Elos Nitrate Test kit NO3 in our view presents some inconsistencies, even compared to the old Elos test we have tried over the years.

The first incongruity regards the height at which the vial must be held from the reference cardboard at the moment of comparison with the color scale.

Many years ago it was clearly written in the instruction to keep the vial 5 cm above the cardboard, but today this indication is no longer present, and we can’t know why.

Moreover the zero lately is indicated by white colour reference.

Truly zero should be on yellow, which is the reference color of reagent B. In fact, even if we look at the reference card of Ocean Life Nitrates Test, which is built with the same reagents, we see that in the reference the zero is not white but yellow.


One of the things I like to mark is the dropper of the bottle, that is extremely accurate, and the drops are almost always identical to themselves.

Elos claims to use a calibrated dropper, thing we can not verify, but, in any case, the result is very remarkable.

Of course, sometime it might happen that a drop is filled by air and bangs, but my experience shows me a chance lesser than one drop for every box…

I advise you to swirl the bottle before using the reagent.


In the rear of the box you can read the reagents used, then also listed in the leaflet with instructions for use.

Elos fits the expiration date stamped with the date by which you should open the test, useful to understand if the test kit is good or not.


We remember that all test kits, although they have a high number of measurements, should be used not more than 6 months from their first use, in order to prevent incorrect storage can ruined the reagents.

I recommend you always use your eye to evaluate the acquarium, do not rely only to test, and if the test were to detect a value clearly wrong, before making any countermeasure would be desirable to do it again with other brands deemed reliable.

Of course, an eye should check the expiration date, which essential for such perishable reagents, especially if exposed to moisture and heat. In addition to calibrate dropper, that for a tritation test is absolutely critical, the mode of packaging and conservation are fundamental for right readings.

Finally you can download the instruction manual here: Nitrates Elos Test Kit manual


The test kit is not cheap since it costs 23,09 €, but given my experience over time, I can also say results have always been in line with what is in the aquarium, given the many comparisons I’ve done with other tests.

And the price is, in my opinion, the only limiting factor in this test. In addition to the question about the heigh we have to maintain the vial during the reading and it is also not so clear what color should be the zero reference, if white or yellow, as I consider to be more correct, in contrast with what is reported in the color reference.

For these reason, considering the read values absolutely true, we believe this test absolutely reccomended, but given the price a bit ‘high value for money can not be higher than 3 and a half stars.

Build Quality 4hstar
Quality 4star
Value for money 3hstar
Final Thoughts

For these reason, considering the read values absolutely true, we believe this test absolutely reccomended, but given the price a bit 'high value for money can not be higher than 3 and a half stars.

Overall Score 3.5