nitrite in cycled tank

[sunshine]

:-[Hello, everyone.  

I have had my aquarium for 2 monthes now.  The cycling process has been over for atleast a month (Am I correct in thinking this since the levels dropped to 0?).  Everything was going fine until last night when I checked the levels.  The ammonia level is normal, the PH is usual, but the nitrite level has gone from 0 to 0.25 ppm.  I checked again today and the level is still at 0.25.

I have been doing 10% water changes every week.  I have been vaccuming every 2 weeks.  I thought that I was doing ok.  What could have gone wrong?  What should I do to correct the problem?  Please can someone help!  Should I do a water change?  Thanks. ???

Also I have a ten gallon tank with 4 dwarf frogs, 2 guppies, and 2 cory cats.  Biowheel filter.

 

[JWright]

Have any fish gone missing recently? A decomposing body could cause an ammonia/nitrite spike.

Are you sure of your test results?

If you're sure of the results (or even mostly sure) then I would reccomend a water change to get the level down (repeat as needed).

I would also reccomend you increase the amount of water you change weekly (25-30%), and vaccum the gravel with each water change.

Josh