OK My ammonia cycles lasted 38 days in a 12 gallon system 12 tank with 4 zebras. I'm curently on my 31st day on the nitrite cycle, no dead fish and all apear to be Ok. My filter I think could really use a changeing would this be OK. I've cleaned some excess build up off of it in the past but I really think going into my third month I could use a new filter. My biological filter is well established so I thought changeing the regular filter would be OK.It appears the my nitrite levels are falling, there currently around .10 to.15 a light blue color not the aqua blue that reads zero. Any input would be great.