Quick and accurate test strips.Test for pH Nitrite Nitrate General Hardness (GH) and Carbonate Hardness (KH).For freshwater or marine aquariums. Desiccant-lined tube with snap-tight cap (25 pack) or individual sealed strips (4 pack) provides maximum moisture protection for accurate results.Dip directly into your aquarium water and compare the colour against the colour charts.Includes information on how to correct unsafe water conditions; see the paper insert (in the 25-pack) or click on the Documents button to the left of this text.