Quote Originally Posted by Photo Engineer

Ammonium Ferric EDTA solution (50 - 60%) 200 ml
Ammonium Bromide 150 g
Disodium EDTA 10 g
Ammonium Sulfite 10 g

Dissolve in 500 ml water and bring to 1 liter. Adjust pH to 6.5 with 28% acetic acid.

This is the response I was trying to make when I posted "garbage".
How important is the Ammonium component of this recipe?

I mean if one were to replace NH4Br with KBr or NaBr and (NH4)2.SO3 with Na2SO3 or K2SO3 and adjust the quantities to maintain the same concentrations of Br and SO3 in solution, what would be the effect/s other than a tendency to buffer at different pH before correction with acetic acid (or -say- Na2CO3)?