Tetra Test 6in1 - a dip test for checking 6 water quality indicators in just 60 seconds. - Tests for pH Nitrite Nitrate KH (carbonate hardness) GH (general hardness) and chlorine- Easy and quick to use - 6 readings in 60 seconds.- 10 Strips. Simply dip the test strip in the water for a few seconds and then wait a minute for it to change colour. Then just compare the colours to the chart on the pack to get your readings. Always read the instructions before use.It is recommend to test every 2-3 days in new aquariums and once a week in established aquariums.