What caused my mini cycle?

[Miyavp]

I had my betta tank cycled and he got a fungal infection. So I had to take the carbon filter out to medicate. I put it in a tubaware container with tank water and put it back in between treatments which was every other day when I switched water and remedicated. Then he got better I put the filter back in and everything looked fine. Then I got some root tabs for my westeria plants and I put one in but my betta unburied it. So I did a 50% water change to remove any added nitrogen to the water and added more gravel and a new better plant bulb. That was yesterday. Today I noticed his gills were a little red so I tested the water and did a 50% water change. .25ppms of ammonia before the water change and no nitrites. I didnt test the nitrates cause I'm super tired. What might've caused it? And do I just recycle the tank like I did before?

 

[shellieca]

It's possible the meds affected the BB & its possible that it being out of an ammonia source killed off some as well. It shouldn't take long to get back into sync but like you're already doing just keep an eye on it.