Ammonia & pH

[Edwin_Thom]

Hi Randy,

This chart shows the pH of ammonia is >11 (strong alkaline).

http://www.drhelm.com/aquarium/phdiagram.gif

In a tank with non-matured biofilter, will high level of ammonia cause the tank water to have high pH as well ?

[Randy Holmes-Farley]

It is true that ammonia is quite basic. If you added a lot of straight ammonia to an aquarium, the pH would rise.

However, when ammonia is produced in aquaria, there is also acid produced at the same time. More acid, in fact, than ammonia, so if anything the pH declines.

Here's the equation for the aerobic degradation of organics (as happens in a fish eating fish food):

(CH2O)106(NH3)16(H3PO4) + 106 O2 ---> 106 CO2 + 106 H2O + 3 H+ + PO4--- + 16 NH3

where (CH2O)106(NH3)16(H3PO4) is the chemical formula for a typical organic naterial (like fish food or plankton)

The H+ and CO2 (which hydrates to carbonic acid, H2CO3)produced are more than acidic enough to offset the basicity provided by the ammonia.

[Edwin_Thom]

Many thanks Randy, for the detailed explanation. :thumbsup:

[Randy Holmes-Farley]

You're welcome.

Happy reefing. :)