Hey, I have an established 10gallon tank, and Im in the beggining stages of cycling a new 33gallon. I had a cat fish die in the 10g, so I tested, nitrite was up a bit, I did a 25% water change and treated it with some Prime. a few hours past and my other fish were acting up.. Real twitchy like.. No other signs of stress though.. I immediately moved them to the 33g, because my cycle hasn't really started yet.. They all seem to be doing just fine now.. but i'd like to get them out and back in the 10g before the cycle gets too harsh for them.. any tips on how to bring the nitrite back down?? also can anyone tell me why this might have happened for future prevention?? thanks a lot!!