My tank is cycled, i know. But somehow theres 7.0 ppm!!! What happened?! The tank is "self sustaining" to an extent. Snails breed, puffer eats snails, mollies nibble algea and plants, and they all get a cube of brine shrimp a week. I just drop the cube in. Its hard for me to clean the tank without disturbing the plants, as they havent gotten a foothold in roots. But everything was normal, until just a random 7.0 ppm!!!! Gaaaahhh!!!