I am hoping someone can tell me what is going on. I unfortunately bought a new 33 gallon tank almost 6 weeks ago and the next day bought some fish. (1 Heroes Notatus(South American Cichlid), A Raphael Catfish, 6 Neon Tetras, 3 Glass Catfish and a goby Dragon) If I knew then what I know now then I would have waited for the addition of the fish. I used cycle, did 30% water changes every couple of days, sometimes every day if the ammonia levels or later the nitrite levels got too high. My ammonia levels dropped to 0ppm about 2 1/2 weeks ago and the nitrites began to spike. I started to decrease the frequency of the water changes at the advice of my local pet store to reduce the stress on the fish. Well yesterday the nitrite levels started to drop and today I have a reading of 0ppm. I was thrilled 5 weeks 3 days and I was cycled. Just for fun I tested the ammonia and it is up from 0ppm to 0.25 ppm. Am I starting over again? I have not added any fish. I did use mardel to treat for fungus but this was complete over a week ago and have been assured that this would not hurt my cycle. Please HELP me understand I can't find any other incidents of this happening.
Cheryl

There are several articles on this sight -- most are easy to understand

Freshwater Fish Tank | eHow Search

Think it is a juggling act keeping a healthy home for fish

Hey Cheryl,
Hun, I think you're just fine.
Often you will get an ammonia reading after a new tank has fully cycled because perhaps you fed too much, or cleaned a little too much, or changed filter cartridges, or changed a little too much water, or even cleaned gravel, disease treatments, there are numerous reasons that cause damage to beneficial bacteria.
If you did a disease treatment, it would make sense that you are seeing the effects it had on the cycle a week later.
Keep an eye on it to see if it continues to spike, watch the nitrites too for a rise.
You can add a dose of Cycle and don't do any water changes...
This will help build stronger beneficial bacterial colonies so that less accidents occur with damaging the cycle during regular maintenance
And disease treatments.

Your tank needs about a month after the cycle is complete to really establish itself.

Let me know if you have anymore concerns and I'll be happy to help.