Hydrion Insta-Chek Paper Test Strips pH - The Ultimate in many, General Purpose papers have a different colour to match each full pH unit: 0.0] [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11.0] [12] [13]. Hydrion insta-chek pH papers offer: a direct reading pH paper with the widest range in a single a simple, single colour for all pH values unique and easy to pair colour frequency distances accurate, reproducible measurements with an immediate response hydrion wide range pH paper is a paper test strip general use. A sample of pH diverse applications are: classroom demonstrations, hospital, laboratory, general laboratory, industry testing, food service emergency safety, testing, testing, agriculture in vitro tests simply tear off a small strip of paper test strips, dip into the solution, then immediately compare the colour with the appropriate pH colour palette. - The colour paper has changed significantly from salmon to green colour. This tape is not to test any type of water because of water ion content. Should you use li5900 or li5000 to test water.