- Location
- Connecticut
Recently, I became interested in the chemistry of my aquarium's substrate and wanted to test for ammonia in the 0 to 0.2 ppm range. I bought several hobby kits, hoping to find one with this type of sensitivity. Salifert, Elos, Seachem and API were the kits I chose to test. Ammonia standards were prepared from serial dilutions of a stock solution of newly prepared Instant Ocean saltwater spiked with ammonium chloride. Since I owned a Salifert ammonia test kit, I began the trials with this test kit.
I hold Salifert test kits in high regard, so, I was surprised to find that the kit underestimated the ammonia concentration and indicated 0 ppm for a 0.5 ppm standard (see picture below). Until testing the kit with a reference standard I had no idea. I purchased a new test kit thinking something happened to the reagent since I purchased it even though the expry date was still a half year off. The new kit performed similarly. It detects ammonia, but only approximately.
I then tested the Elos test kit. It did work at all. No color change. Was I not following the directions correctly or was I just having bad luck purchasing test kits?
Next I tested the API test kit and it worked. Not only did it work, it was about one third the cost and provided two half times as many tests as Salifert or Elos. The potential downside was that the test solution color for 0.1 ppm ammonia was almost impossible to distinguish from 0 ppm. Only by a side by side comparison with a test solution at 0 ppm ammonia could I reliably detect the test response at 0.1 ppm ammonia (see photo).
I had one more look at the Elos test kit when I realized it and API use the salicylate method. When I replaced the Elos oxidizer solution with the API oxidizer solution, the Elos test kit responded to ammonia. I did not try to optimize the Elos test performance with the API reagent. So, it appears that I can follow directions after all and just had bad luck purchasing test kits.
Seachem was the last test kit I examined. This kit uses a reusable film that changes color on exposure to ammonia. As you can see from the photo below, detecting ammonia concentrations below 0.2 ppm is possible, but underestimates the ammonia concentration. In the second photo, the test film images were moved on top of the color scale. Notice that the response to 0.2 ppm is pretty good, but the response to 0.1 ppm is low but different from the test response to 0 ppm ammonia.
Conclusion. The Seachem test will be used to detect but unfortunately not quantify ammonia concentrations below 0.2 ppm. Secondly, when a test kit indicates 0 ppm, it does not mean the test sample is ammonia free, but that it is below the limit of detection. An important distinction to make, especially when cycling a new aquarium or determining why fish are dying.
I hold Salifert test kits in high regard, so, I was surprised to find that the kit underestimated the ammonia concentration and indicated 0 ppm for a 0.5 ppm standard (see picture below). Until testing the kit with a reference standard I had no idea. I purchased a new test kit thinking something happened to the reagent since I purchased it even though the expry date was still a half year off. The new kit performed similarly. It detects ammonia, but only approximately.
I then tested the Elos test kit. It did work at all. No color change. Was I not following the directions correctly or was I just having bad luck purchasing test kits?
Next I tested the API test kit and it worked. Not only did it work, it was about one third the cost and provided two half times as many tests as Salifert or Elos. The potential downside was that the test solution color for 0.1 ppm ammonia was almost impossible to distinguish from 0 ppm. Only by a side by side comparison with a test solution at 0 ppm ammonia could I reliably detect the test response at 0.1 ppm ammonia (see photo).
I had one more look at the Elos test kit when I realized it and API use the salicylate method. When I replaced the Elos oxidizer solution with the API oxidizer solution, the Elos test kit responded to ammonia. I did not try to optimize the Elos test performance with the API reagent. So, it appears that I can follow directions after all and just had bad luck purchasing test kits.
Seachem was the last test kit I examined. This kit uses a reusable film that changes color on exposure to ammonia. As you can see from the photo below, detecting ammonia concentrations below 0.2 ppm is possible, but underestimates the ammonia concentration. In the second photo, the test film images were moved on top of the color scale. Notice that the response to 0.2 ppm is pretty good, but the response to 0.1 ppm is low but different from the test response to 0 ppm ammonia.
Conclusion. The Seachem test will be used to detect but unfortunately not quantify ammonia concentrations below 0.2 ppm. Secondly, when a test kit indicates 0 ppm, it does not mean the test sample is ammonia free, but that it is below the limit of detection. An important distinction to make, especially when cycling a new aquarium or determining why fish are dying.
