If you have a pH test kit that gives a yellow color at about 6pH and blue at about 7.2 pH, such as the Aquarium Pharmaceuticals test kit, you can use that test reagent. I am not impressed by the reagent sent out with the ebay drop checker. From what you are describing I wonder just what the stuff in the bottle you have really is. Bromothymol Blue indicator, which it should be, is yellow in the reagent bottle, but turns blue in typical tap water.