I'm cycling a bare 29g tank and my nitrites seem to be stuck around 2.0 ppm. They have been there for over 2 weeks and my other tanks all had their nitrite spike and fall in about a week. My ph is 6.8-7.0 Ammonia showing 0.25 ppm and my nitrates are at least 40 ppm (Salifert test only goes up to 40 ppm). I can't decide whether to do a partial water change now or wait a bit longer to see if the nitrites drop. Suggestions?