Colombo NO2 Test

Nitrite should always read zero in a healthy pond. The Colombo NO2 Test helps you detect nitrite (NO2) quickly and accurately, so you can act before fish are put under stress.

Nitrite builds up when your biological filter isn’t fully matured or is struggling. Even low levels can affect koi, especially during start-up, after cleaning filters or when feeding increases.

Why nitrite matters

• Indicates how well your biological filter is working
• Can rise during new pond start-ups
• Often appears after heavy cleaning or medication
• Essential to monitor in spring and after adding fish

Regular testing keeps you in control and prevents small issues becoming bigger problems.

What’s included

• Liquid drop test reagents
• Test tube
• Colour comparison chart
• Instructions

Clear colour changes make results easy to read and compare.

When to test NO2

• During new pond cycling
• After adding new fish
• Following filter maintenance
• If fish appear stressed or inactive

Good practice & safety

• Rinse the test tube with pond water before and after use.
• Store reagents in a cool, dark place.
• Keep chemicals out of reach of children and pets.