[rsman]

I wouldnt say nitrate is more toxic than nitrite even though it seems to be much less toxic than in FW and both are much less toxic than ammonia.

there is nothing especially unreliable with a well built coil denitrator, aside from it being a bio filter to begin with, (something we already have to rely on very significantly) the sulfur ones are no better or worse in this regard, just smaller, and more $$ in both initial cost and running costs