OK so I was doing my weekly water change on one of my tanks (10g)
Right after the water change I tested my perameters, and I got
Nitrite > 5
I am sure you can imagine my initial response. This tank has been cycled and established for over a year with no problems (minus some algea flareups from time to time)
So I waited for the tank to settle (there was still some floaties from the substrate when I tested the first time) and tested again, waited 5 minutes and got the following results
I was initially worried that I had somehow caused my tank to get back into a cycle some how but I haven't changed anything other than my water changes in quite awhile. A month ago I had cleaned some algea of some decor but other than that, no new fish, no dead fish, no increase or decrease in light or feeding, etc.
So I guess what I want to know is, can Nitrites and Nitrates "settle" in the substrate? and if so Should I be concerned about that initial reading? does it matter?