Aqua One QuickDrop Nitrate NO3 Test Kit - Suitable for Tropical and Marine

I tested this kit against an API test kit and they are pretty accurate, the colour is easy to decipher as the colours are all different. If you have problems seeing colour, as colour always looks different with different light then the Aqua one kits will make that easy. TIP stand under a light that is 6500K and place the tube on the circle of the colour chart and look from the top. avoid warmer light.