I'm assuming you've checked the use by date and its not expired. Also a lot of meds expire quicker after they've been exposed to the air so if you used the same bottle this time that you did 5 months ago then is that work thinking about?dazbud said:just an update on this thread. I used Interpet Fungus and Finrot treatment again this week and the same thing happened. Slight ammonia reading after 1 day. Slight Nitrite reading within 48hours. Cloudy water on day 3. Its definitely the treatment that causes a mini cycle. beware !