You are quite right about the progression Schmill. The ratio for nitrites is 2.7 ppm for each ppm of nitrite. When it continues through to nitrates, the ratio is 3.6 to one.
Oops, my bad then! Sorry about that, I had thought it was 3.6 ammonia to nitrIte, but now you mention the 2.7 that does ring a faint bell in the distance of my mind - lol
