[dburns865]

I want to switch my filter from my freshwater tank, to my brackish tank. Im just curious if this would kill the bacteria in them. The brackish has a tetra whisper and it looks really ugly in there. The other tank is heavily planted and the filter would be mostly covered up. Is this possible or would it start the cycle over?

 

[Sakura8]

I believe, from what I was told by my LFS people, that the bacteria from a marine or brackish filter would die off in freshwater. When I was thinking about starting a small SW tank, I thought about seeding the filter using some freshwater fish I had but they told me, the bacteria would not survive the transition to saltwater and vice versa.

 

[Hallyx]

My understanding is the bacteria that convert ammonia to nitrite (nitrosomonas) are the same for fresh or saltwater. The ones that convert nitrite to nitrate are different.

What that means for your brackish cycle is obscure. But logically it seems it would still promote a cycle, not die-off entirely.