Tetra test nitrate kit is suitable for freshwater and marine aquariums and includes 45 testsr nitrate is produced from the breakdown of nitrite in the filter nitrate can be harmful to fish and high levels may indicate a general decline in aquarium conditionsr regular testing will help you to assess the overall health of the environmentr how it worksr the tetratest nitrate kit is a liquid kit which works by changing the colour of a water sample in relation to the nitrate concentrationr you