mg/L are considered the same as ppm.
And yes, we may be on the same page, I believe our discussion is healthy, as in all of science, skepticism on all sides is the rule, not the exception.
The way I read the research, at very low concentrations, the authors of a number of studies seem to be concluding that deformations such as curved spines, etc, etc in fry can be caused by elevated nitrate.
This also coincides loosely (at least to me) with the effects baby formula made from water with nitrate concentrations of 10ppm or higher, such as blue baby syndrome in human children under 2 years.
I have been interested in the effects of elevated nitrate for a number of years.
Before I became "obsessive" about water changes, I would notice spawns in my tanks, with more deformations/mutations in my fry, than I thought normal.
After changing my water change routine, the percentages seemed to lessen considerably.
And I have received groups of fry from experienced aquarists, that on close examination had a high percentage of major, and minor deformities, knowing full well their was no ammonia burn, and parent fish appeared to be perfect, and the aquaristic standard practices were of high quality.
My conclusion is that nitrate, although thought to be benign, may be the overlooked
culprit.
I believe for most casual aquarists, an elevated nitrate level may be of little to no consequence.
But when dealing with and breeding sensitive species that are rheophillic nature (I prefer to keep Theraps , Chuco and Tomocichla), and/or come from other pristine conditions, (waters with nitrate levels of <1ppm), slight elevation can become a problem.
The great lakes of Nicaragua, rift lakes of Africa, and unpolluted rivers around the world normally have nitrate concentrations of <1ppm.
In my job, I tested raw Lake Michigan water, other than during sewage overflow events, the raw water would test <1ppm.
And as you know, we see many posts here, of stress induced diseases such as HITH, or bloat, where "all" parameters are "normal".
My feeling is the acceptable aquarium concentration norm for nitrate, is not low enough.
