It was fully cycled with -0- ammonia, -0- nitrItes and 20 nitrAtes for a few months now. Have done routine 10-25% water changes since. Not sure why it is cycling again. But the ammonia has shot up (4.0), nitrItes reappear at 0.25 and nitrAtes are 40 now.

So the core question is, what should I do now? Understanding that I need my nitrItes to come up again to take care of the ammonia, so does that mean I should do a large (30-40%) water change to lower my nitrAtes in order to allow the nitrItes to return?

Please help.


Thanks in advance.