my tank has been setup 2 months now and was cycled I have 7 neon tetras but added a bristlenose plec 2 days ago and now my ammonia is about 0.10-0.25 ppm since I added the the plec my nitrite is still 0 and my nitrates about 0.20ppm, I did a 25% water change and the reading is still the same. is my tank going through a mini cycle and what should I do?