If I put my new filter cartridge in with the filter on my cycled tank how long would it take for the bacteria to attached to it? I have MTS and got another used 10gal off Craigslist. I want to use it for breeding red cherry shrimp. I took the filter cartridge out of it and put it in the filter of my large cycled tank. How long would I have to leave it there in order to seed my tank? I'm not putting any fish in that tank so I don't want to lose the cherries when I first put them in. Any suggestions? Maybe I should get a couple of little fish just to test it out? I have Rasbora in my big tank how are they on cycling? If they're good I could move them into my big tank with no problem.