Ammonium/ammonia ratio as a function of pH value

NH₄/NH₃	Proportion of toxic ammonia [mg/l]
Total content	at pH value					Rating
[mg/l]	6	6.5	7	7.5	8
0.1	<0.001	<0.001	0.001	0.002	0.006
0.2	<0.001	<0.001	0.001	0.004	0.011	harmless
0.3	<0.001	0.001	0.002	0.006	0.017
0.5	<0.001	0.001	0.003	0.01	0.029
0.8	<0.001	0.002	0.005	0.015	0.046
1	<0.001	0.002	0.006	0.019	0.057
1.2	<0.001	0.002	0.007	0.023	0.069	critical
1.5	<0.001	0.003	0.009	0.029	0.086
2	0.001	0.004	0.012	0.038	0.114
4	0.002	0.008	0.024	0.076	0.229
6	0.003	0.011	0.036	0.114	0.342	acutely
8	0.004	0.015	0.048	0.152	0.458	dangerous
The table refers to 24 °C water temperature (according to Krause)

The dependence of the ammonia content on the pH can also be calculated using the following formula:

NH3 = 0,94412 * NH4 / (1 + 10 ^ ((0,0925 + (2728,795 / (t + 273,15 ))) - pH))

An ammonia concentration from 0.02 mg/l already represents a hazard (marked in pink). From 0.2 mg/l there is an acute danger to life (red marking).