Since the tests for our aquariums just read the total ammonia content in the water, the question has come up how much of that ammonia is actually toxic? This is a complicated question, which really has to do with the ammonia-ammonium equilibrium, ammonia being toxic, ammonium being comparatively much less toxic. Ammonium is not harmless, there is evidence it interferes with the normal salt exchange at the fish gills, but it is not anywhere as dangerous as ammonia.

Also I'd just like to make it clear that any level of ammonia will cause health problems. Ammonia can cause gill damage, that could become permanent, and a very recent article ("Low levels of environmental ammonia increase susceptibility to disease in Chinook salmon smolts " by Ackerman PA, Wicks BJ, Iwama GK, Randall DJ in PHYSIOLOGICAL AND BIOCHEMICAL ZOOLOGY volume 79 JUL-AUG 2006) showed that fish exposed to low levels of ammonia were more susceptible to disease later on in life. But this mini-article is about when emergency action needs to be taken.

The split between the two species (ammonia and ammonium) is determined by equilibrium. The chemistry reaction can be written as:

NH3 + H+ <--> NH4+
(ammonia) + (H+ ions) <--> (ammonium+ ions)

The +'s indicating a charge of +1, and <--> indicating that the reaction can go both ways.

pH is a measure of the concentration of H+ ions. pH really means -log(base 10) of H+. For example, pH of 7.0 means a concentration of 10^-7 H+ ions, a pH of 5.0 means a concentration of 10^-5 H+ ions.

Therefore the lower the pH, the higher the concentration of H+ ions.

Now, with more H+ ions present, the above equilibrium chemical reaction gets pushed towards the right hand side. This is known as Le Chatelier's Principle. But, Le Chatelier's is a general rule, it does not give us the exact splits.

The calculate the splits, we need the equilibrium constant K = [NH3][H+]/[NH4+] where [] stands for the concentration of the species in the []'s. K is a function of temperature, so experimentation needed to be performed, and some high level computations (well beyond the scope of this mini-article) needed to be performed.

Clegg, S. and Whitfield, M did that experiment. (Their paper is "A chemical model of seawater including dissolved ammonia and the stoichiometric dissociation constant of ammonia in estuarine water and seawater from -2 to 40 deg C. Geochimica et Cosmochimia Acta Volume 59, 1995.) They found the equilibrium constant as a function of temperature and salinity.

So with this information, I calculated what % of the total ammonia in the water would be toxic ammonia and ammonium.

How to use the following tables

Know your pH and temperature.
Look up the % toxic ammonia on the following charts for your temp and pH
Know how much ammonia you have in your tank
Multiply your ammonia content by the looked up percentage
If this number is over 0.02 ppm, then immediate action needs to be taken.

Example:
I have a tank at 27 deg with pH 6.6 water and 2.0 ppm of ammonia.
% toxic ammonia (from) the chart is: 0.045%

2.0*(0.00045)=0.008 ppm toxic ammonia, so it is not immediately dangerous, though exposure to any ammonia is unhealthy for the fish.

Note that if the pH of that tank was over 8.0, the level of ammonia would be immediately deadly, so pH does count!

Also, these are only for freshwater, if there is enough demand I might be talked into making up the equivalent charts for saltwater tanks, but not now.

20 deg C or 68.0 deg F
=============
pH ... % toxic ammonia
=============
9.0 ... 9.6835
8.8 ... 6.3363
8.6 ... 4.0937
8.4 ... 2.6225
8.2 ... 1.6709
8.0 ... 1.0608
7.8 ... 0.6719
7.6 ... 0.4250
7.4 ... 0.2686
7.2 ... 0.1696
7.0 ... 0.1071
6.8 ... 0.0676
6.6 ... 0.0427
6.4 ... 0.0269
6.2 ... 0.0170
6.0 ... 0.0107
5.0 ... 0.0011
4.0 ... 0.0001


21 deg C or 69.8 deg F
=============
pH ... % toxic ammonia
=============
9.0 ... 9.7474
8.8 ... 6.3797
8.6 ... 4.1224
8.4 ... 2.6412
8.2 ... 1.6829
8.0 ... 1.0685
7.8 ... 0.6768
7.6 ... 0.4281
7.4 ... 0.2706
7.2 ... 0.1709
7.0 ... 0.1079
6.8 ... 0.0681
6.6 ... 0.0430
6.4 ... 0.0271
6.2 ... 0.0171
6.0 ... 0.0108
5.0 ... 0.0011
4.0 ... 0.0001


22 deg C or 71.6 deg F
=============
pH ... % toxic ammonia
=============
9.0 ... 9.8113
8.8 ... 6.4231
8.6 ... 4.1511
8.4 ... 2.6599
8.2 ... 1.6949
8.0 ... 1.0762
7.8 ... 0.6817
7.6 ... 0.4312
7.4 ... 0.2725
7.2 ... 0.1721
7.0 ... 0.1087
6.8 ... 0.0686
6.6 ... 0.0433
6.4 ... 0.0273
6.2 ... 0.0172
6.0 ... 0.0109
5.0 ... 0.0011
4.0 ... 0.0001


23 deg C or 73.4 deg F
=============
pH ... % toxic ammonia
=============
9.0 ... 9.8751
8.8 ... 6.4664
8.6 ... 4.1798
8.4 ... 2.6786
8.2 ... 1.7069
8.0 ... 1.0838
7.8 ... 0.6866
7.6 ... 0.4343
7.4 ... 0.2745
7.2 ... 0.1734
7.0 ... 0.1095
6.8 ... 0.0691
6.6 ... 0.0436
6.4 ... 0.0275
6.2 ... 0.0174
6.0 ... 0.0110
5.0 ... 0.0011
4.0 ... 0.0001


24 deg C or 75.2 deg F
=============
pH ... % toxic ammonia
=============
9.0 ... 9.9388
8.8 ... 6.5097
8.6 ... 4.2085
8.4 ... 2.6973
8.2 ... 1.7190
8.0 ... 1.0915
7.8 ... 0.6915
7.6 ... 0.4374
7.4 ... 0.2764
7.2 ... 0.1746
7.0 ... 0.1102
6.8 ... 0.0696
6.6 ... 0.0439
6.4 ... 0.0277
6.2 ... 0.0175
6.0 ... 0.0110
5.0 ... 0.0011
4.0 ... 0.0001



25 deg C or 77.0 deg F
=============
pH ... % toxic ammonia
=============
9.0 ... 10.0025
8.8 ... 6.5530
8.6 ... 4.2372
8.4 ... 2.7159
8.2 ... 1.7310
8.0 ... 1.0992
7.8 ... 0.6964
7.6 ... 0.4405
7.4 ... 0.2784
7.2 ... 0.1758
7.0 ... 0.1110
6.8 ... 0.0701
6.6 ... 0.0442
6.4 ... 0.0279
6.2 ... 0.0176
6.0 ... 0.0111
5.0 ... 0.0011
4.0 ... 0.0001


26 deg C or 78.8 deg F
=============
pH ... % toxic ammonia
=============
9.0 ... 10.0661
8.8 ... 6.5963
8.6 ... 4.2658
8.4 ... 2.7346
8.2 ... 1.7430
8.0 ... 1.1069
7.8 ... 0.7013
7.6 ... 0.4436
7.4 ... 0.2804
7.2 ... 0.1771
7.0 ... 0.1118
6.8 ... 0.0706
6.6 ... 0.0445
6.4 ... 0.0281
6.2 ... 0.0177
6.0 ... 0.0112
5.0 ... 0.0011
4.0 ... 0.0001


27 deg C or 80.6 deg F
=============
pH ... % toxic ammonia
=============
9.0 ... 10.1296
8.8 ... 6.6396
8.6 ... 4.2945
8.4 ... 2.7533
8.2 ... 1.7550
8.0 ... 1.1146
7.8 ... 0.7062
7.6 ... 0.4467
7.4 ... 0.2823
7.2 ... 0.1783
7.0 ... 0.1126
6.8 ... 0.0711
6.6 ... 0.0449
6.4 ... 0.0283
6.2 ... 0.0179
6.0 ... 0.0113
5.0 ... 0.0011
4.0 ... 0.0001


28 deg C or 82.4 deg F
=============
pH ... % toxic ammonia
=============
9.0 ... 10.1931
8.8 ... 6.6828
8.6 ... 4.3232
8.4 ... 2.7720
8.2 ... 1.7671
8.0 ... 1.1223
7.8 ... 0.7110
7.6 ... 0.4498
7.4 ... 0.2843
7.2 ... 0.1796
7.0 ... 0.1134
6.8 ... 0.0716
6.6 ... 0.0452
6.4 ... 0.0285
6.2 ... 0.0180
6.0 ... 0.0113
5.0 ... 0.0011
4.0 ... 0.0001


29 deg C or 84.2 deg F
=============
pH ... % toxic ammonia
=============
9.0 ... 10.2565
8.8 ... 6.7260
8.6 ... 4.3518
8.4 ... 2.7906
8.2 ... 1.7791
8.0 ... 1.1300
7.8 ... 0.7159
7.6 ... 0.4529
7.4 ... 0.2863
7.2 ... 0.1808
7.0 ... 0.1142
6.8 ... 0.0721
6.6 ... 0.0455
6.4 ... 0.0287
6.2 ... 0.0181
6.0 ... 0.0114
5.0 ... 0.0011
4.0 ... 0.0001


30 deg C or 86.0 deg F
=============
pH ... % toxic ammonia
=============
9.0 ... 10.3198
8.8 ... 6.7692
8.6 ... 4.3805
8.4 ... 2.8093
8.2 ... 1.7911
8.0 ... 1.1376
7.8 ... 0.7208
7.6 ... 0.4560
7.4 ... 0.2882
7.2 ... 0.1820
7.0 ... 0.1149
6.8 ... 0.0726
6.6 ... 0.0458
6.4 ... 0.0289
6.2 ... 0.0182
6.0 ... 0.0115
5.0 ... 0.0012
4.0 ... 0.0001


31 deg C or 87.8 deg F
=============
pH ... % toxic ammonia
=============
9.0 ... 10.3831
8.8 ... 6.8123
8.6 ... 4.4091
8.4 ... 2.8280
8.2 ... 1.8032
8.0 ... 1.1453
7.8 ... 0.7257
7.6 ... 0.4591
7.4 ... 0.2902
7.2 ... 0.1833
7.0 ... 0.1157
6.8 ... 0.0730
6.6 ... 0.0461
6.4 ... 0.0291
6.2 ... 0.0184
6.0 ... 0.0116
5.0 ... 0.0012
4.0 ... 0.0001


32 deg C or 89.6 deg F
=============
pH ... % toxic ammonia
=============
9.0 ... 10.4463
8.8 ... 6.8554
8.6 ... 4.4378
8.4 ... 2.8467
8.2 ... 1.8152
8.0 ... 1.1530
7.8 ... 0.7306
7.6 ... 0.4622
7.4 ... 0.2922
7.2 ... 0.1845
7.0 ... 0.1165
6.8 ... 0.0735
6.6 ... 0.0464
6.4 ... 0.0293
6.2 ... 0.0185
6.0 ... 0.0117
5.0 ... 0.0012
4.0 ... 0.0001


33 deg C or 91.4 deg F
=============
pH ... % toxic ammonia
=============
9.0 ... 10.5094
8.8 ... 6.8985
8.6 ... 4.4664
8.4 ... 2.8653
8.2 ... 1.8272
8.0 ... 1.1607
7.8 ... 0.7355
7.6 ... 0.4653
7.4 ... 0.2941
7.2 ... 0.1858
7.0 ... 0.1173
6.8 ... 0.0740
6.6 ... 0.0467
6.4 ... 0.0295
6.2 ... 0.0186
6.0 ... 0.0117
5.0 ... 0.0012
4.0 ... 0.0001


34 deg C or 93.2 deg F
=============
pH ... % toxic ammonia
=============
9.0 ... 10.5724
8.8 ... 6.9416
8.6 ... 4.4950
8.4 ... 2.8840
8.2 ... 1.8392
8.0 ... 1.1684
7.8 ... 0.7404
7.6 ... 0.4684
7.4 ... 0.2961
7.2 ... 0.1870
7.0 ... 0.1181
6.8 ... 0.0745
6.6 ... 0.0470
6.4 ... 0.0297
6.2 ... 0.0187
6.0 ... 0.0118
5.0 ... 0.0012
4.0 ... 0.0001


35 deg C or 95.0 deg F
=============
pH ... % toxic ammonia
=============
9.0 ... 10.6353
8.8 ... 6.9846
8.6 ... 4.5236
8.4 ... 2.9026
8.2 ... 1.8513
8.0 ... 1.1761
7.8 ... 0.7453
7.6 ... 0.4716
7.4 ... 0.2980
7.2 ... 0.1883
7.0 ... 0.1189
6.8 ... 0.0750
6.6 ... 0.0474
6.4 ... 0.0299
6.2 ... 0.0189
6.0 ... 0.0119
5.0 ... 0.0012
4.0 ... 0.0001

This post has been edited by Bignose: Aug 19 2006, 03:57 AM

This is a very interesting article. I'm not joking, I'm being sincere.

This post has been edited by Bullrock74: Aug 18 2006, 11:38 PM

How long did it take you to write this?

But, no matter. Truly, it was a good article.

-Lynden

10 mins to write the text, 10 mins in Excel (I didn't do all that by hand), 10 mins to format the charts so that they would display correctly on the forums. I actually just expanded on the work I did for your ammonia thread the other day, so a lot of it was already done.

Good work. Maybe somebody will pin it.

If anyone wants it I've converted bignose's table back into Excel and added a lookup function - enter the temp in c, the ph and nh3/4 combined reading and it gives the % and nh3 values.

PM with an email addy as I can't attach it and I'll send it.

I can see that from your charts that if you have a high PH and a High temperature the same amount of Ammonia is more toxic to your fish if you had a low PH and a low temperature. In conclusion than people with high temps an PH should be more wary of their ammonia levels. I feel that it would be useful if something could be added to the calculator page below using your findings?

http://www.fishforums.net/aquarium-calculator.htm

Darryl

Bignose,

I have read that 0.05 is the toxic threshold line for numbers coming out of a temp/pH calculated toxicity chart like that. You have used 0.02 and I wonder if any choice of number in this range is subjective, I guess it would be to some extent.

Congrats on a nice clear explanation that covers all the details nicely!

~~waterdrop~~