Freshwater vs saltwater bacteria

[jasonrusso]

So I've been using a 10 gallon tank for holding my saltwater (1.018 sg) feeder shrimp for my predator tank. I was planning on starting to use freshwater shrimp, mollies, etc. as a treat.

Can I use the same media that is in the tank because it is established? I have some live rock chunks in the 10 gallon now. I'll rinse them off in RO and then fill up the tank with freshwater hopefully not having to cycle the tank again.

 

[jack_aubry]

My thinking would be no. You could use the same media, but the bacterial communities will be largely if not completely different. You could always test it, but I think the marine bacteria will die off and it will take time for the freshwater communities to establish.

 

[jasonrusso]

I'm not sure either. The reason I ask is because most of the bacteria say "Marine and Freshwater. "