Description

This article is from the Beginning Fishkeeping FAQ, by Thomas Narten with numerous contributions by others.

29 How Much Ammonia Is Too Much?

In an established tank, ammonia should be undetectable using standard
test kits available at stores. The presence of detectable levels
indicates that your bio filter is not working adequately, either
because your tank has not yet cycled, or the filter is not functioning
adequately (e.g., too small for fish load, clogged, etc.) It is
imperative that you address the problem (filter) in addition to the
symptoms (high ammonia levels).

The exact concentration at which ammonia becomes toxic to fish varies
among species; some are more tolerant than others. In addition, other
factors like water temperature and chemistry play a significant role.
For example, ammonia (NH3) continually changes to ammonium (NH4+) and
vice versa, with the relative concentrations of each depending on the
water's temperature and pH. Ammonia is extremely toxic; ammonium is
relatively harmless. At higher temperatures and pH, more of the
nitrogen is in the toxic ammonia form than at lower pH.

Standard test kits measure total ammonia (ammonia plus ammonium)
without distinguishing between the two forms. The following chart
gives the maximum long-term level of ammonia-N in mg/L (ppm) that can
be considered safe at a given temperature and pH. Again, note that a
tank with an established biological filter will have no detectable
ammonia; this chart is provided only for emergency purposes. If your
levels approach or exceed the levels shown, take emergency action
IMMEDIATELY.

                            Water Temperature
                pH      20C (68F)       25C (77F)
                _________________________________
                6.5     15.4            11.1
                7.0     5.0             3.6
                7.5     1.6             1.2
                8.0     0.5             0.4
                8.5     0.2             0.1

 

Continue to:

• prev: 28 What Is the Nitrogen Cycle?
• Index
• next: 30 Minimizing Fish Stress During Initial Cycling

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