yea, your tank is not cycled, if it were nitrites would be zero. nitrites are toxic to fish, nitrates are acceptable in small amounts. the good bacteria you are attempting to grow with a cycle consume nitrites and convert them to less harmful nitrates. so to have any nitrites, essentially means you dont have enough bacteria to eat it.
it sounds like a bloom to me, up your water changes. also, are you testing for ammonia? very important!
it sounds like a bloom to me, up your water changes. also, are you testing for ammonia? very important!