Tetra Test O₂ Oxygen

=”Tetra Test O2 Oxygen is a simple to use kit for determining oxygen levels aquariums and ponds. It is a liquid type of kit which works by changing the colour of a water sample in relation to the oxygen concentration. You simply need to compare the colour o”&”f the sample to the easy-to-read colour chart to determine the oxygen level. Always read the instructions carefully before use.