I’m a big fan of the API master test kit for testing the basic water conditions of my fish tank. You test the water in your aquarium too, right? If you don’t you should start, I highly recommend the API Freshwater Master Test Kit
The problem is, my nitrates always read 0ppm. For an established tank, that can’t possibly be right. The nitrogen cycle should be converting waste and everything into nitrates. I have a lot of plants in my tank, but not that many.
It turns out there may be a problem with some of the test kits where the liquid in bottle #2 settled. Fixing it is easy enough. Just bang the bottom of the test solution bottle on a table or something a few times and shake well for a minute or three.
When you run your test again, you’ll find your nitrates no longer read 0. Mine went from zero to about 15-20, right where they should be. Hat tip to Fishlore for this one.