Hmm, I've reviewed the thread carefully and I can't find any mention of the OP having issues with cyanobacteria (BGA). Unless BGA was mentioned in another related thread, this is all about Black Brush Algae (BBA). If so this is undoubtedly a CO2 issue.
Cyanobacteria (BGA) is related to inadequate NO3, not necessarily inadequate CO2, and I'm fairly certain that the demonstrations have shown this correlation.
ATP synthesis and consumption occurs in every plant cell, to a lesser or greater degree, the balance of the two being dependent on many things including nutrient and CO2 availability. Specific deficiencies (as well as their acuteness) affect a specific combination of processes which are expressed in certain ways, so I'm not really sure the equation shown clarifies any deficiency expression (at least not in a plant). In fact the equation appears to show basic atmospheric nitrogen fixation, which could easily describe a bacterial metabolic pathway - and a very expensive pathway at that, since it appears to require a massive 16 ATP molecules to complete.
The result of ATP consumption is typically liberated inorganic Phosphate (Pi) via ATP (Adinosine Triphosphate) conversion to ADP (Adinosine Diphosphate). Not only that, but the result appears to produce ammonia, which is highly toxic and if this is some sort of diazotrophic process, would then have to be somehow assimilated, maybe by protein action into glutamate.
I guess I'm not sure what imbalance or possible explanation is implied by this equation. The equation itself is out of context because it does not, for example, explain where the 8 electrons are coming from. There would be a related equation to show the reaction of ferredoxin (iron-sulphur protein which mediates electron transfer) with some enzyme which executes the electron transfer, perhaps something like nitrogenase reductase. The 8 protons would be generated by some other equation possibly describing a hydrogenase enzyme acting on Hydrogen and separating the 8 electrons. So really, these are fundamental reactions that don't really imply anything other than basic life processes. I can't detect any imbalance there. Tom would have a better grip on it though.