could have gotten a dud or maybe its expired? (i know you say its new but could have been sitting on the shelf for a long time)
no, checked that. expiry 11/2019
I know a lot of people say test kits aren't accurate; which I can accept
which is why I have stuck to the same brand cause it is the trend, or relative readings, I take note of.
I don't check for nitrates that often once I know how a tank is behaving, but I have just moved a bunch of fish around and added some more fish so some tanks are running with a good stock load. So was just monitoring how my water change regime was going.
Will take it back to the shop - didn't buy it online - see supporting the locals with a water sample and see what they say.