What can cause 'False' Nitrite reading?

[amerpatrt]

I had a huge Nitrite spike and was wondering what things might cause a possible 'false' reading? Can over-the-counter additives do this? Distilled water? (I added some to the tank recently because our tap is high in Nitrates). All the other readings are fine. I will do a partial water change, but am wondering if certain things can cause 'false' readings. Thank you,
Dawn

 

[dwayne]

How do you know it is a false reading?

 

[OrionGirl]

Unlike ammonia, I don't think there is a non-toxic version that could be giving false readings. What's the pH?