I am in the process of cycling my 10 gal tank when it hit me out of no where...my sister has a 5 gal that she's been running for 8-10 months now. If I bought her a new filter and used her old one to help cycle my tank would it uncycle hers? Or would there be enough bacteria established in her tank now to do no harm?? Excuse me for my ignorance-but would I throw my current filter away or would I simply use both filters?