Ammonia/BioFilter question

[RooRoo]

I've been doing a fish in cycle for months now. I think it was started May/June. I keep up with water changes, and check water perameters often. My question is this, if there is no biofilter at all in a tank, 40 gallon, how long would it take for 6 zebra danios to raise ammo levels, and how high would they go in what time frame? I'm asking because I can't seem to keep ammo at zero,but they don't sky rocket either- yet everything else points to the tank being cycled. I've seen nitrites briefly on 3 different occasions and within 2 days the tube was back to bright blue. I have Nitrates, reads steady around 20 last two weeks. I just have trouble with Ammo. It seems like it will hover around .25 for 3-5 days if left without water changes. If left beyond that it has risen to .5 but never above that, and that can take over a week or so to achieve. SO do you think the tank actually is cycled, and I may be over feeding causing the ammo to hover at .25-.5?

Just wondering how high those reading would be without any biofilter at all. Or does Ammo only get to .25 if left alone?

 

[librarygirl]

Hm, the tank should be cycled by now, I would think. Or should be in theory as it's been long enough. I have no idea how much of a bioload six danios in a 40 gallon produce; I wouldn't think it would be huge though, so the slow increase in ammonia makes sense. But, as I said before, if you've been cycling for 3-4 months now it should be done and ammonia should be 0. What test kit are you using? Has it expired? What is your PH level (if your PH is very low that could explain the problems)?