Worried about crashing my nitrogen cycle

[RachelElizabeth]

I am wanting to switch out my filter, but don't want to totally crash my nitrogen cycle. I set up my 25 gallon >6 months ago, and so far I've been running the hang-on-back filter that came with the tank. I believe its a Top Fin 30. I recently bought a similar-sized Aqua Clear that I would like to use instead since I have heard so many good things about them. However, I have been hesitating to swap them because of effects on the overall beneficial bacteria populations. One thing that I think will help is that I also have an established sponge filter running that will be staying in the tank, and I have a pre-filter sponge that's been on the old filter that would be transferring over to the new Aqua Clear. Please let me know your thoughts about how much this swap will affect my cycle. Thanks!

[lefty o]

just do it. you have the pre-filter sponge, and everything else in the tank is covered in good bacteria. if it still concerns you, run both hang on backs for a few days, then remove the old one.

[Isaac M]

Hello @RachelElizabeth, I do not anticipate it will hurt your beneficial bacteria very much. All the surfaces in your aquarium have beneficial bacteria, the sponge filter and the pre-filter. I would personally not hesitate to make the swap.