I did my weekly water change last night in my 20g and ran some tests today. My ammonia and nitrates were fine, but I was showing 0.25 ppm of nitrites. These always read zero since my tank cycled sometime last year, and I haven't had any deaths or additions to my tank. What could be causing this? The only thing I can think of is that I could have stirred up more stuff than usual because I moved a bunch of decor around to gravel vac under it.
Any reason to be worried? I'm probably over-reacting, but right after the test I started looking at plans to build a sponge filter