Odd Nitrite spike!

[ppo8820]

I have a 10 gallon with 1 baby angel (he will be moved later) 2 endlers, and 2 snails. It has been cycled and had constant 0 readings, but out of the blue, I got a nitrite spike. I did a water change and discovered a dead apple snail in the hornwort. I removed it, and then tested after water change, and it was back to 0 nitrites. Then 24 hours later, tonight, I tested again and it was back up to 1.0 Nitrites. Why would this be happening?

 

[Mebbid]

Did you test your ammonia?

 

[ppo8820]

I think it was a cycle due to a deceased snail I didnt realize was dead in my hornwort.