Chemistry

hey peeps i am in a spot of bother my new set up has been running for a good 3 weeks. All the stock came from a mature set up so it was well established. I have been checking water levels every 3 days yet the only thing that is at 0 is my nitrites!!! my ammonia is still and has always been 0.25 and phosphates 0.5!!! i havent even seen a bloom in algea or an other growth. i know cycles are different and cycles can take anything up to 6 weeks to complete but it seems like it has not begun???...