1. Not finding help here? Sign up for a free 30min tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Nitrate and pH in a Fishlessly-cycled Aquarium

  1. Jun 18, 2011 #1
    1. The problem statement, all variables and given/known data

    Prior to introducing livestock, a fishkeeper may establish colonies of nitrosifying and nitrifying bacteria by repeatedly inoculating an aquarium with a solution of ammonia (to simulate the presence of fish). At the end of the process there is a high concentration of nitrate in the water - typically of the order of 80mg/l.

    May such a concentration of nitrate lower pH?


    2. Relevant equations

    [none understood]

    3. The attempt at a solution

    And anyway, what kind(s) of nitrate is it? Cations can come only from the virgin water (usually tapwater) in which there is typically a preponderance of calcium and magnesium. Is calcium nitrate more likely than magnesium nitrate? I have read that the former's pH is around 4 or 5 ; while the latter's is around neutral. So if calcium nitrate forms there'll be a heap of extra H+ ions around ...

    ... which is fine so long as there's sufficient buffer (in the form of bicarbonate) to soak them up. If not, then presumably high nitrate in low-buffered water would indeed tend to acidify? Would nitric acid form?

    Or am I on the wrong track altogether?
     
  2. jcsd
  3. Jun 19, 2011 #2

    Borek

    User Avatar

    Staff: Mentor

    The only thing I can think of is that oxidation of ammonia can acidify the solution:

    NH3 + 2O2 -> HNO3 + H2O

    You don't produce calcium or magnesium nitrate, these cations were in water and they are still there, nothing have changed.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Nitrate and pH in a Fishlessly-cycled Aquarium
Loading...