Ammonia Alert

  • Seachem sensor technology
  • Continuously monitors ammonia
  • No tests, no strips
  • Marine and freshwater


Ammonia Alert® is an innovative color device for continuously detecting and monitoring toxic free ammonia. A sensor changes reversibly from yellow to green to blue, relative to the ammonia concentration. No test kits, chemicals, or procedures are needed. The device detects less than 0.05 mg/L (ppm) free ammonia and alerts you to the #1 killer before any sign of stress. It lasts over a year. Marine or freshwater use.

In the absence of free ammonia the unit will assume a yellow or faint yellow-green color. It is normal for the dry sensor to have a greenish hue. It may take up to a few days for a dry sensor to equilibrate with the water. No sampling of water, chemicals, or test procedures are required. The presence of the free ammonia is detectable continuously with a response time of about 15 minutes. Response to decreasing ammonia is slower, requiring about 4 hours to go from TOXIC to SAFE on removal of ammonia.

Ammonia Alert® lasts over 9 times as long as competing products (over a year compared to 4-6 weeks). Ammonia Alert® is also almost half the size of competing products (1.5" x 2.5"). It's small, clear, and unobtrusive, so it won't detract from the view of your aquarium.


As little as 0.02 mg/L of free ammonia will produce a greenish hue on the detector surface. This corresponds to a total ammonia (both ionized and free ammonia) of 0.25 mg/L in marine water at pH 8.3. In freshwater at pH 7.0, this corresponds to 3.6 mg/L total ammonia. Free ammonia is much more toxic than ionized ammonia. As free ammonia, the ALERT color corresponds to about 0.05 mg/L, ALARM to about 0.2 mg/L, and TOXIC to about 0.5 mg/L. The ALERT concentration is tolerated for several days, ALARM for a few days, and TOXIC is rapidly harmful. For emergency ammonia removal, treat with AmGuard™. This product is not recommended for use at acid pH.


No care is required beyond removing algae with a clean, soft material. Avoid touching the sensor with fingers, since skin oils can damage it. Do not use bleach, soap, detergents or hard objects to clean the sensor. Some dye medications may discolor the sensor. Sensitivity improves with age, provided the unit is not allowed to dry out, however, drying does not permanently impair the unit. For maximum sensitivity, the unit should be read under natural daylight or daylight simulating light. Red enhancing light minimizes green and blue hues, decreasing the apparent sensitivity of the unit. The response of the unit may be checked by holding it briefly over the mouth of an ammonia bottle: color should develop rapidly.

A: The Ammonia Alert sensor should last about a year before you should need to replace the sensor. To test it gently hold the card over a bottle of ammonia; the sensor should quickly change to a dark blue. It may take about an hour for it to return to its original color.

A: Most likely the other test kit was testing for total ammonia. Total ammonia includes both free (NH3) and ionic (NH4+) ammonia. The Ammonia Alert only measure free ammonia because that is the harmful form. Ionic ammonia cannot harm your fish. However, as pH rises, a greater and greater percentage of the total ammonia will be converted from ionic ammonia to free ammonia, so knowledge of total ammonia is also important.

A: If the Prime has not complexed with the ammonia yet it will detect it, but it won't detect it if the Prime has already complexed it (which makes sense because when Prime has complexed with the ammonia it is no longer toxic). If you want to know the total ammonia level (free, ionized and complexed) you would need to run a Total Ammonia Test (like with our MultiTest Ammonia.

A: The technology of this device is very unique to our company and has been an excellent seller for many years to hobbyists, breeders, and public facilities alike. The Ammonia Alert is designed to change color in the presence of free (gaseous) ammonia, not ammonium (ionized ammonia) which is harmless to fish and other aquatic life. The longer it is left in a particular body of water/aquarium, the more sensitive it becomes to that water. Most conventional test kits test total ammonia which is a combination of free ammonia + ammonium = total ammonia. PH is the determining factor on what type is present. If your pH is acidic (below 7.0), it is chemically impossible for ammonia (harmful gas) to exist. Yet a total ammonia test kit will register a reading because it detects both the free ammonia (harmful gas) and ammonium (harmless ionized form of ammonia). The more basic your pH becomes, the greater the chance of ammonia existing. Example: If you have 1.0 ppm of total ammonia and your pH is below 7.0, then 1.0 ppm will exist as ammonium. Ex. If you have 1.0 ppm of total ammonia and your pH is 7.6 (slightly basic), then of that 1.0 ppm total ammonia......only .2 or so would exist as a gas and the other .8 would exist as ammonium.

There is one simple way to tell if our Ammonia Alert is functioning properly, simply hold the sensor over an open bottle of something containing ammonia (Windex glass cleaner will work) as it will detect the fumes/gas and change color. Please be sure not to touch the sensor in the middle of the plastic card as the oils from your skin may clog the pores on the sensor.

A: Yes it does work accurately, however as a product like Ammo Lock is removing the ammonia the transition back to yellow will take some time, so don't be concerned if you don't see an immediate shift back to yellow. The Ammonia Alert is always faster to respond to increasing ammonia levels than to decreasing.

A: The greyish color indicates the "Alarm" state of ammonia. Was it grey or yellow when you took it out of the package and placed it in the tank? If it was yellow when you put it in and is now "grey" then that means you have a high level of ammonia and should do a water change very soon or treat with our AmGuard if a water change is not feasible within 24 hours.

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