I've had my 29g tank for almost 3 months now. It has yet to cycle! The ammonia is finally down to a safe level but the nitrites are very high, at about 2.0ppm. My nitrates have just recently shot up to 20ppm. What am i doing wrong? I changed the water 10% every couple of days to bring down the ammonia and that worked but its not helping the nitrite levels. I purchased three plants being told it would help with Nitrite and i've had them for over a week now, still haven't seen a change. I haven't been able to put new fish in my tank since i've gotten it cause i want the water chemistry to be good. I have 5 fish left. Also if this makes a difference, ive been changing my filter cartridge once a month, now i'm being told you shouldn't? Whats up with that?