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How The Testing Was Done

        Five test solutions were chosen that were known to have pH’s in the range of aquarium pH test kits. These were: 1) A sample of "typical" aquarium water of pH 7.1, 2) A hydrochloric acid solution of pH 6.80 0.01, 3) A sodium bicarbonate (baking soda) solution of pH 7.30 0.01, 4) A sodium hydroxide solution pH 7.70 0.01, and 5) Analytical buffer solution (clear) of pH 7.00 0.01. The hydrochloric acid solution was prepared from analytical grade 0.1376M stock solution. The sodium hydroxide solution was prepared from the anhydrous solid weighed on an analytical balance to the nearest 0.001 grams and dissolved in ultra-pure de-ionized water.

        Five identical vials were each filled with one of the test solutions and were labeled. The labels were obscured and the vials were mixed to a random order. A test kit was chosen and a vial was selected randomly for testing, until all vials had been selected. The tests were performed exactly following the respective manufacturers’ instructions included in the packaging. The results of the tests were recorded. The pH of another sample of the same solution was then checked with an analytical pH meter (accurate to 0.01 units) and those results were recorded. The label was then removed from the vial and the identity was noted. This procedure was repeated for each test kit.

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