API Nitrite Test Kit, 180 Tests

The API Nitrite Test Kit is a liquid reagent test for nitrite in freshwater and saltwater aquariums. It includes 1 bottle of testing solution, 1 color card and 1 test tube with cap, enough for 180 tests (model 26). The color card reads from 0 to 5 ppm.

Why test nitrite

Nitrite is the middle step of the nitrogen cycle: bacteria turn ammonia into nitrite, then nitrite into nitrate. High nitrite inhibits fish respiration and suppresses their immune systems. In a new tank, nitrite usually rises after ammonia falls, and the tank is not ready until it drops back to zero.

When to test

API suggests weekly monitoring and testing when water or fish problems appear. During cycling, test every day or two. After a big filter cleaning, a medication course or a power outage, check nitrite for a few days, since bacteria may have been knocked back.

Why a single-parameter kit

If you already own a master kit, the nitrite reagent often runs out first during a long cycle. A separate kit is a cheap refill. It is also a good buy if you only need to track the cycle and use strips for everything else.

Accurate results

• Fill the tube to the line exactly.
• Hold the bottle upside down so drops are uniform.
• Cap and shake, wait the stated time, and read against white.
• Rinse the tube with clean water afterward.

If nitrite shows

Do a partial water change, reduce feeding and keep the filter running. In freshwater, a small dose of aquarium salt is a common way to reduce nitrite toxicity; check that your fish tolerate salt first. A bacteria product such as MICROBE-LIFT Nite-Out II can help the colony recover.

Related tests

Pair it with API Ammonia Test Strips to watch both stages of the cycle.