Hi..

By accident I once subjected a tankfull of plants and
Ammano shrimp to 200ppm nitrate for 3 week. No ill effects
whatsoever.

200 ppm == 200 milligrams per litre

Richard, sorry but what shall it show us..?

Amano shrimps are brackish shrimps and brackish animals are
well known to be very very very tolerant relating to high
leveled NH4+, NO2-, NO3-- ..!!!

High NO3 concentrations might inhibit the fertilisation rate
of the Amanos but unfortunately Amanos aren't able to
reproduce in freshwater - even not if it's
NO3_contaminated..! ;-)

Just another data point.

Absolutely..! :-)

--
cu
Marco, wondering and wondering and wondering..