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How Ammonia Testing Works

     The simplest and most common ammonia test kit is one that uses Nessler’s Reagent, or a slightly modified version of it. With this kit type, you place a known volume of aquarium water (usually 4-6 milliliters) in a clear test vial. Three to eight drops of Nessler’s Reagent is then added to the test vial. After 2-3 minutes, the resulting color of the solution is compared to a color gradient total ammonia chart to determine the concentration in either ppm-NH3 or ppm-N(itrogen) [ppm = parts per million and is equivalent to mg/L, milligrams per liter]. Variants of these types of kits also exist in which the liquid indicator is replaced by a powdered, granular, or tablet form of indicator............

How The Testing Was Done

     Five test solutions were chosen that were known to have total ammonia levels in the range of aquarium ammonia test kits. These were: 1) A sample of "typical" aquarium water of NH3 < 0.05 ppm (as a blank), 2) An ammonium chloride (NH4Cl) solution with NH3 = 0.5 ppm, 3) An ammonium chloride solution with NH3 = 1.0 ppm, 4) An ammonium chloride solution with NH3 = 1.5 ppm, and 5) An ammonium chloride solution with NH3 = 2.0 ppm. The ammonium chloride solutions were prepared from anhydrous solid ammonium chloride weighed on an analytical balance to the nearest milligram and dissolved in ultra-pure de-ionized water. An example preparation would be: 2.0 ppm NH3 = 2.0 mg/L NH3 X 3.14 g NH4Cl/g NH3 = 6.28 mg/L NH4Cl -- weigh 62.8 mg NH4Cl and dilute to volume in a 100 ml volumetric flask (0.628 mg/ml). Take 10 ml of this solution and dilute to volume in a 1 L volumetric flask (6.28 mg/L NH4Cl).

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