Blackwell Synergy - Freshwater Biol, Volume 50 Issue 1 Page 27 - January 2005 (Article Abstract)

There is a fair amount of evidence that suggest that what I said 10 years ago about NH4 may be correct in both aquariums and lakes. Other studies have shown similar results. This is a fairly wide ranging one.

Such studies have a hard time pin pointing precisely where a N threshold is, I do as well in our aquariums, but I do believe that light/NH4/Fish/stability of the plant biomass plays a huge role, the same might be said in these cases as well.

Such wide ranging data from various fields offers a good level of support to a working model to CO2(DIC in these cases) and NH4 role in algae blooms in the presence of macrophytes.

While some want to carry on ad nauseum about their subtle NO3 and PO4 balances being some sort of "key" or that "less is better", the reality in the science suggest and has suggested otherwise for at least 20 years.
Myself, about 10 years.
I had no idea about these publications as I'd never read a paper really back then but I know enough to see that it was not NO3, it was not O2, it was likely NH4+. Later I realized that it was very much CO2 as well as NH4 together.

Regards,
Tom Barr