Am I being cruel??

It's possible because it's not cycled, so you remove, but it builds right back up again.

The behavior you describe sounds normal for danios.
 
Thanks didy. So, getting 0 readings for what seemed like forever, followed by a crazy spike in Nitrites just means I'm in the second stage of the cycle, right?

I did another 25% water change tonight. Basically, I'm doing them every other day until my chemistry improves. Is that too often? Not enough? The sticky on cycling a tank doesn't say how often to do water changes during the cycling process.
 
Test your water every day. If you're in the middle of a major spike, test twice a day. Any time Ammonia or Nitrite are above .25ppm, change out whatever volume of water is necessary to get you below .25ppm. For example, if your water were testing .50ppm Nitrite, then you would need to do a minimum 50% water change to get it back down below .25ppm. Basically, let your test readings dictate your water changes. That way you're keeping the toxicity down for the fish.
 
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