Hi

I am somewhat of a newbie to garden ponds, although have kept aquariums in the past. I live on the Isle of Wight, so no big fluctuations in temp. I have a pre-formed 60 gal pond, planted with oxygenators, water lettice, and marginals. I have an internal pump feeding a UV Fishmate filter that runs onto a waterfall. The pond in several weeks old now and was filled with water from the stream behind my house. Inhabiting my pond are 4 very small common goldfish. My query is that although tests for ammonia, pH, and O2 are all good I have a constantly high Nitrite level. I have tried 1/2 water changes and added Zeolite to the filter system. It is my understanding that ammonia oxidises to nitrate and then nitrite......so how come there is no ammonia but levels of nitrite are at 0.5ppm?

All help greatfully recieved, julie