Acceptable Ammonia Level

Ammonia exists in 2 forms in water, ammonia and ammonium. The amount in each form depends on the pH and temperature. Ammonium is a lot less toxic than ammonia. Our test kits test for both combined, but we can use a  calculator to work out how much is in the toxic ammonia form.

https://www.hamzasreef.com/Contents/Calculators/FreeAmmonia.php

Set salinity to zero, and enter your ammonia reading, pH and temp on the left, then click calculate. The number you want is in the lower box on the right - NH3 concentration.

If that number is below 0.02, the fish are safe. If it is between 0.02 and 0.05, you will need to do a water change soon. If it is above 0.05, do a water change now.




The main reason for saying it is safe up to 0.25 with our test kits is just that 0.25 is the lowest reading above zero with most testers.