wrote in message
ups.com...

It seems Paul had found that 20-80 ppm and above was the ideal range
for submersed plant growth(Vallisneria americana) back in the
1960's(1966). I suppose I redisocovered this range(20-75ppm)
independently some 30 years later thropugh trial and errors.

What is interesting is that we both arrived at the same range. At
progressively high concentrations, this high rate of growth slowly
decline, but very slowly.....even at 100ppm etc.

This also mirrors my own observations when I did longer term NO3 at
75ppm for several weeks.

What is really interesting is how rapid the growth rate increases when
the level is maintained.

Hi Tom,
Though I am only a layman, these levels of nitrate seem a little
frightening, especially to an ex-marine hobbyist. I always thought that
anything over 30ppm caused real stress in any fish stock (though I repeat,
I'm only a layman). The higher levels, 50ppm plus, must surly have a
detrimental effect on any of the slower growing plant species? After all
eutrophication has proved to be a problem in many smaller bodies of water,
though I need to admit that I'm struggling to understand the chemistry
involved. Just put it down to my age and the resultant death of brain cells
;o)
Regards David