Originally Posted by pop
Bacteria in the Freshwater Aquarium states “Autotrophic bacteria synthesize their own food, and they require oxygen so they are termed aerobic. Some do this via photosynthesis using sunlight, oxygen and water. Others use chemosynthesis, a process whereby they manufacture carbohydrates from carbon dioxide (CO2) and water using chemical nutrients rather than sunlight as the energy source.”
Do these autotrophic (aerobic) bacteria that require oxygen also produce carbon dioxide in the process sometimes referred to as aerobic respiration?
If this is correct the nitrifying bacteria in a cycled aquarium reloads carbon dioxide into the water Column.
What happens when the water column is in a state of oxygen deprivation will the autotrophic bacteria reverse the process and stop production of nitrates and begin converting nitrates to nitrites to ammonia or would the lack of oxygen cause the bacteria colonies to shut down?
the whole tank crashes.
the nitrates->nitrItes->nitrogen gas usually requires a low oxygen environment only found in the substate. Not in the water column itself.
the nitrates->nitrItes->ammonia also in the subatrate when a deep sand bed (DSB) is malfunctioning. Not in the water column
the Natrual Nitrate reduction(NNR) through bacteria is a big thing in marine systems up to 4-5 years ago. After several years of being recommended by everyone with all kinds of operational "secrets" to keep it going, some experienced and expert systems started crashing after 5 years or so of operations. Since then algae system usually in some kind of refugium have returned to various discussions.
In any event reducing nitrates with low oxygen bacteria leads to cyano bacteria problems.
While your concern is valid, it actually just points to using plant life to reduce nitrates instead of low oxygen methods. At least with plants consume carbon dioxide and return oxygen. Not to mention using ammonia/nitrates as well as phosphates.