Whats the difference between hobbyist level nitrate testing and non hobbyist level testing,,, I am guessing that means vendors,,, how are they, non hobbyist,, testing differently than the rest of us?
I have been fighting a Nitrate battle in my tank,,, started in 100 range with my Salifert test kit

I have it down to the low end of the 25 range,,, just a tad more and I will be in the 10 range,, did a couple of large water changes,, a couple smaller water changes as the number got lower,, have been dosing 10 ml of vinegar per day,,, used a sand vacuum , ran the hose into a filter sock and cleaned the sand bed, really good,, in the tank except under my rock,,, running my skimmer wet,, feeding my fish a lot less,, any less and the fish won't be eating ,, like I said,, got the number down to the low 25 range and that number is staying there,,, for several weeks,,, cant crack into the 10 range,,, now I am wondering how good that number really is that I am getting from my Salifert test kit,, never thought about getting another test kit and trying that,,,