Ammonia Alert - Continuous Ammonia Sensor

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Ammonia Alert is an innovative color indication device for continuously detecting and monitoring toxic free ammonia. There's no need to wait for signs of stress or death in your fish or corals to take action against an ammonia spike. With the Ammonia Alert card, you can always tell at a glance if trouble is brewing and take preventative measures before things get out of hand. The color-change indicator will give you an early warning if even small amounts of ammonia are building up, giving you time to find the source, do a water change, and dose additives to bring the levels back down to a safe range. 


  • Seachem sensor technology
  • Continuously detects and monitors free ammonia
  • No test kits, chemicals, or procedures are needed
  • Lasts over a year
  • Marine and freshwater

The Ammonia Alert card is small, clear, unobtrusive, and can be placed in the display or in a high visibility area of your sump so it won't detract from the view of your aquarium. The sensor changes reversibly from yellow to green to blue, relative to the ammonia concentration. No test kits, chemicals, or procedures are necessary. The device displays less than 0.05 mg/L (ppm) free ammonia and alerts you to the #1 killer before any sign of stress. What’s more, this simple and life-saving device can last over a year.

Usage Notes

  • 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.
  • 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. In freshwater at pH 7.0, this corresponds to 3.6 mg/L total ammonia.
  • The ALERT concentration is tolerated for 3-5 days, ALARM for 1-3 days, and TOXIC is rapidly harmful, requiring immediate attention. Administering a water change should be considered for any indication other than SAFE. For emergency ammonia removal, we recommending considering treatment with an ammonia neutralizing water conditioner such as ClorAm-X and a bacterial cycling additive such as Dr. Tim’s One & Only or MicrobacterStart XLM.
  • 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.
  • The response of the unit may be checked by holding it briefly over the mouth of an ammonia bottle: color should develop rapidly.


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. This product is not recommended for use at acid pH.

More Information
UPC 000116001007
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Product Questions

What is the lifespan of this sensor?
Question by: Derek Meekma on Jan 16, 2022, 5:02 PM
The Ammonia Alert® sensor should last about a year before you should need to replace the sensor.
Answer by: Matt Lucero (BRS Staff) on Jan 17, 2022, 12:07 PM