|| PH > > >
||Table of Free Ammonia
| || 0.0 is ideal. Values up to 0.019 might be tolerated for extended periods||
| || 0.020 - 0.049 may be tolerated, but will cause long term harm
| || 0.050 - .0.199 May be tolerated for a few days, harmful
| || 0.200 - 0.499 May be tolerated for a day or two, very harmful
| || >0.500 Extremely Toxic, remove fish
|What is 'free' versus 'ionized' ammonia?
Free ammonia (NH3-N) and ionized-ammonia (NH4+-N) represent
two forms of reduced inorganic nitrogen which exist in equilibrium depending
upon the pH and temperature of the waters in which they are found.
Of the two, the free ammonia form is considerably more toxic to fish and,
therefore, we pay considerable attention to the relative concencentration of this particular
Existence of these chemical species are generally viewed as indicators that a given water
has been contaminated, usually in relation to the direct discharge of an ammonia-bearing waste (e.g., fish waste, uneaten food, rotting leaves, something dead in system, etc.).
Just how toxic
is free ammonia?
The U.S. EPA's criteria for free ammonia toxicity
are presented in terms of system pH and temperature for both total
ammonia and un-ionized ammonia (NH3) according to both 1-hr values and 4-day averages.
The U.S. EPA recommends that these levels should not be exceeded more than once in
three years...which would enable a system to recover from the stress which would have
been caused by ammonia pollution.
This approach implicity recognizes that some degree of fish
mortality is acceptable.
For aquaculture systems, published recommendations are as
low as one-tenth of the U.S. EPA's recommended concentrations in order to avoid killing fish.
|Notes:||The formulas used here are based upon work by Professor James E. Alleman, Purdue University
I'm confident this calculator is accurate, but things happen. Use it at your own risk,