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API Freshwater /Saltwater Nitrite Test Kit, Test kit of 180 tests


Item #: AP3111

Temporarily Out of Stock

Tests for nitrite in freshwater & saltwater aquariums. Toxic nitrite is produced by nitrifying bacteria in the biological filter as it breaks down ammonia. This kit tests for harmful nitrite and measures levels from 0 to 5.0 ppm. 180 tests per kit.

Freshwater/Saltwater Nitrite Test Instructions:

Why Test For Nitrite?
Nitrite (NO2-) is produced in the aquarium by the biological filter. Beneficial bacteria in the biological filter convert toxic ammonia into nitrite (also toxic). The biological filter then converts nitrite into nitrate (NO3-). Testing for the presence of toxic nitrite is essential, so that once detected, steps can be taken to remove it. Otherwise, nitrite in the aquarium will prevent fish from carrying on normal respiration. High levels of nitrite quickly lead to fish death. Even trace amounts of nitrite stress fish, suppressing their immune system and, thereby, increase the likelihood of disease and subsequent fish loss.

Testing Tips:
This test kit reads total nitrite (NO2-) level in parts per million (ppm) which are equivalent to milligrams per Liter (mg/L) from 0 ppm to 5.0 ppm, in either fresh or saltwater aquariums. Other nitrite test kits that measure “nitrite-nitrogen” (NO2-N) will give readings 3.3 times LESS than this test kit.

Directions for Testing Nitrite:
  • Read thoroughly before testing. Do not allow test solutions to get into aquarium.
  • To remove childproof safety cap: With one hand, push red tab left with thumb while unscrewing cap with free hand.
    • Fill a clean test tube with 5 ml of water to be tested (to the line on the tube).
    • Add 5 drops of Nitrite Test Solution, holding dropper bottle upside down in a completely vertical position to assure uniformity of drops added to the water sample.
    • Cap the test tube and shake the tube for 5 seconds. Do not hold finger over the open end of the tube, as this may affect test results.
    • Wait five minutes for the color to develop.
    • Read the test results by matching the color of the solution against those on the Nitrite Test Color Chart. The tube should be viewed against the white area beside the color chart. Color comparisons are best made in a well-lit area. The closest match indicates the ppm (mg/L) of nitrite in the water sample. Rinse the test tube with clean water after each use.
What The Test Results Mean:
  • In new freshwater and saltwater aquariums the nitrite level will gradually climb to 10 ppm (mg/L) or more. As the biological filter becomes established (in 4 to 6 weeks), nitrite levels will drop to 0 ppm (mg/L). In an established aquarium, the nitrite level should always remain at 0 ppm (mg/L). The presence of nitrite indicates possible over-feeding, too many fish, or inadequate biological filtration.
  • The nitrite level is not an indication of the ammonia level; ammonia is another toxic waste material which must be tested separately.
Monitoring Nitrite Levels:
Regular testing for nitrite is an essential part of routine aquarium maintenance. Aquarium water should be tested for nitrite once a week to make sure the nitrite does not reach undesirable level.

Reducing Nitrite in the Aquarium

Use Aquarium Pharmaceuticals Nitra-Zorb™ to remove nitrite from freshwater aquariums. Nitra-Zorb is a rechargeable filtration material that removes nitrite from freshwater. Making partial water changes can also help reduce the nitrite level, especially if the initial nitrite level is very high. Use Aquarium Pharmaceuticals STRESS ZYME® to help speed the development of the biological filter. Adding Aquarium Pharmaceuticals Aquarium Salt will reduce nitrite toxicity to fish while the biological filter is removing the nitrite.

Partial water changes will lower nitrite in a saltwater aquarium. Use Aquarium Pharmaceuticals STRESS ZYME to help speed up the development of the biological filter.

  • Causes burns. Harmful if swallowed.
  • Contains hydrochloric acid. Avoid contact with skin and eyes. If on skin, flush with water for 15 minutes. If in eyes, hold lids open and flush with water for 15 minutes. Remove contact lens, if present, after the first 5 minutes, then continue rinsing. If swallowed, do not induce vomiting. Call a physician immediately.
FIRST AID: Give large amounts of water or milk of magnesia. Wash thoroughly after handling. Keep out of the reach of children.

Manufacturer information

Aquarium Pharmaceuticals Aquarium Supplies
Aquarium Pharmaceuticals (API) has been helping people take good care of ornamental fish for over 40 years. Their research and development scientists have advanced the care of fish with all-natural medications, stable bacteria for biological filtration, one-bottle test kits, consumer-friendly dosing caps and much more. They’ve received over 25 global patents for their breakthrough innovations in the aquatics industry. And they continue to look for ways to improve the fishkeeping experience for hobbyists. Research. Experience. Dedication to scientific, quality treatment for healthy fish. It’s what makes API the first choice of aquarium owners. API manufactures and sells hundreds of products across many different product categories, including aquarium and pond treatments, aquarium equipment, aquariums and fish nutrition.

5 Stars


Reviewed on
March 03, 2017

Yes, I would recommend this.

great product

Pros: easy to use

I like this nitrite better than salifert. I use salifert to test everything but nitrite and nitrate. this, to me, is easier to read and perform. no powders.

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chris burkett

Reviewed on
July 09, 2013

Yes, I would recommend this.

Good test for Money

Easy test and color chart is easy to read.

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alina perez

Reviewed on
February 02, 2012

Yes, I would recommend this.

Great Product!

It was very simple to use and read the results. Very happy I purchased the product.

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Reviewed on
November 24, 2011

Yes, I would recommend this.


Good for a color chart tester. Fast test results and easy to use. Eventually I will get a digital one for more accurate readings. Since it is a color chart test, I gave it 4 stars

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jaison monaski

Reviewed on
April 18, 2011

Yes, I would recommend this.

Nitrite test

It is good. It tests my water for nitrite.

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katie gonsalves

Reviewed on
January 06, 2010

Yes, I would recommend this.

Simple to Use

I highly recommend this kit as a novice. It was so helpful during the process of establishing my biological filter. My 3 gallon tank took me 8 weeks to balance. I felt more informed using this test kit and didn't just have to rely on my local pet shop to test my water.

Was this review helpful? 0 0

steven d mckay

Reviewed on
June 14, 2009

Yes, I would recommend this.

Aquarium Pharmaceuticals Fresh

Well I could go on and on about how good it is,but it's just a test kit.Simply put it works, It works well.Most of my test kits are from Aquarium Pharmaceuticals,they work and are economical.I would recommend them to everybody.

Was this review helpful? 2 0

david jersey shore

Reviewed on
April 12, 2009

Yes, I would recommend this.


grate test for step 1 in starting up a new fish tank its on the money........

Was this review helpful? 1 0

james oyler

Reviewed on
July 31, 2008

Yes, I would recommend this.

Nitrate Test Kit

This product is economical and works well. It does exactly what it is supposed to do, with good accuracy through color-matching to sample color bars (one set of bars each for freshwater and saltwater, though they aren't very different). The concentration range measurable is good. Overall, excellent product.

Was this review helpful? 9 0

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