I find the whole nitrate subject very interesting, mainly because I don't fully understand it.
The ammonia test we do tests for ammonia, and the nitrite test for nitrite. Both are very bad and we aim for 0ppm on both, always. Pretty straightforward on those two.
I naively thought like the vast majority of other hobbyists that the nitrate test simply give us an indication of nitrate. We've learnt that nitrate isn't as bad as the other two so we have a bit of leeway. The fact that the acceptable nitrate level can differ depending on who you talk to, from single low figures ppm up to say 40-50ppm makes it a grey area of acceptability.
And now we're learning that nitrate really isn't a thing after all, it's the build up of other stuff which the nitrate reading only alludes to, that is the real reason we need to freshen our water up by water changes.
Calling it the "nitrate" test, to me now, just seems outdated. What else would you call it though? And then, taking us straight back to the age old problem, what acceptable ppm would you put on it?