Raised Nitrite

My filter recently lost power for a day or two before I discovered it.
Ammonia levels were up and I lost 2 fish. I rinsed and cleaned the
filter extreely well just using tank water (it was quite smelly) Whne
I was finished it had that normal musty type of odour. i reassemable
the filter and started it up. I was assuming that I would be starting from
scratch again as all the bacterioa must have died. So I added zeolite and
with water changes the ammonia became undetectable. I then deciede that
now was a good time to strip down the whole tank for a clean.

I refilled the tank with tap water and aquaplus to remove chlorine and let
this run with the filter for 24 hours before adding the fish. I
acclimatized the fish in their temp tanks by plenty of small water changes
with water from the "clean" tank setup. I then transfered just the fish
back to the tank.

I never measured for ammonia and nitrite becuase I would be expecting 0. I
kept the zeolite (which I realise would retard the re cycling, but I did
not want to stress the fish out with raised ammonmia levels). After
checking the water a couple of days later I found zero ammonia (the
zeolite doing its work I assume) and raised nitrite(0,3 ppm) I checked the
tap water to be sure there were no nitrtrites. I would not have expected
nitrities so soon - unless the filter is actually working to convert some
ammonia into nitritite, but the filter can clearly not handle all the
nitrities.

Does this sound normal?

Trev