2 filters running, how long to colonise the new one?
I have a brackish water tank running at the moment (S.G. 0.004 and slowly raising by 0.002 each week) I currently have 2 filters running in this tank as I bought a more powerful one to cope with my dirty puffers! The new one has been running alongside the old one for about 2-3 weeks now. My daughter wants to set up her own tank of guppies and I am thinking about taking out one cycled filter to start her tank with. Would it be OK to remove the older one now and would there be enough beneficial bacteria gathered in the new one? Also as the S.G. in my tank is so low will putting the filter back into fresh water damage the bacteria at all or will it still be OK?