What would happen if I use a mature freshwater filter in a newly set saltwater tank?

[belabaru]

I know, I know. Very weird question. But , at the end of the day, the bacteria is the same. Nitrosomas and nitrobacter, isn't it?

Would the bacteria in the filter just die?

Would some of it survive and help with the cicle?

Am I just insane?

[colormegone]

I'd say it would all die a salty death.

[mcarroll]

I think there would be no more than a harsh adjustment – not a total die-off.  Would be interesting to experiment and find out.  (Maybe someone has!)

[KC2020]

 

6 hours ago, belabaru said:

I know, I know. Very weird question. But , at the end of the day, the bacteria is the same. Nitrosomas and nitrobacter, isn't it?

Would the bacteria in the filter just die?

Would some of it survive and help with the cicle?

Am I just insane?

Not a weird question. But not a practical idea.

No the bacteria won't just die. Some will survive. But only after a period of stress during which they won't contribute to the cycle of your tank. If you've seeded the tank with strains from an existing saltwater tank or a culture intended for cycling your tank they will outcompete the freshwater strain before they can adapt.

And yes @mcarroll there has been research on this. I can't site the work I participated in because it was not published for public consumption but this study was.
 

 

 

 

[anizato]

death = algae

 

I would give it a good rinse and drown it for a day in citric acid, finally rinse it in RODI, then use it in for the reef.