Tetratest Ammonia (NH3/NH4+) for Freshwater and Marine Aquariums
Simple to use kit for determining ammonia levels
Application
The Tetratest Ammonia kit is a liquid kit, which works by changing the colour of a water sample in relation to the ammonia concentration. You simply need to compare the colour of the sample to the easy-to-read colour chart in order to determine the ammonia level.
We recommend testing for ammonia every 2-3 days in a new aquarium, and once a week in an established aquarium.
Always read the instructions carefully before use. If ammonia levels are high then you should seek advice as to the underlying cause.
(Source: http://www.tetra-fish.co.uk)