Cycling situation! Opinions needed.

I had a fully cycled tank equipped with a Biofilter. I felt it was producing to much current for my axolotl and switched to a Sponge filter. I left the both on for a few weeks and then pulled the Bio. Now my No2 levels have spiked due to the new filter not having enough growth. I have a few options and I wanted to get some opinions. The No2 Levels were in the high 2's yesterday. I did a %50 water change. He is eating fine, active and his gills and tail show no signs of stress.

I have a 6 gallon fluval Edge tank in my office that has guppies and Cherry shrimp in it. I was considering having him stay there for a few weeks while the No2 levels drop. I know this is not ideal but he's not more than 5 inches so he wouldn't be to cramped.

Just placing him in the fridge for a 1 or 2 weeks while the levels drop.

Letting him stay in the tank and do %25 water changes every other day.

Can I ask what No2 is? Nitrite I imagine. It should be ok if you do a %20 daily change and check levels. could you cram some of the media from your last filter into the new one?

I'm not following. What was your nitrate level in ppm.? If it is a big enough tank and a small axolotl why not just cycle it with the axolotl in the tank?

My Nitrate levels are nearing 3.0 ppm. My tank is 20 gallons and the axolotl is around 5 inches. He seems to be doing fine. Will he/she be ok as long as I do a %25 water change every other day?

I would continue cycling with him in the tank. You will be able to tell if he starts stressing.