Tetra test 6 in 1 water test strips facilitate fast and precise checking of the 6 most important water values in your aquarium the correct water values are vital since incorrect levels can lead to stress and illness for your fish the water testing strips test the following 6 values general hardness carbonate hardness nitrites no2 nitrates no3 chlorine cl2 ph levels note tetra test 6 in 1 water test strips produce accurate results but are only intended as a quick test for a more comp