Originally Posted by Pufferfish22
I have decided to move away from my brackish tank and go over to a freshwater. However I really want to try to avoid having to recycle the tank, I know Molly's do ok in brackish water, if I put some in and gradually reduced the SG over a few weeks would my bacteria in my tank gradually adjust? Also I have driftwood in there, would it have absorbed the salt from the water? I am thinking of gradually reducing the salt and once back to fresh water, washing out the gravel (in conditioned water) and the ornaments to remove the salt
Will I cycle again or should the Molly's prevent this, and how many would I need?
First off, a bit of salt in the driftwood won't really matter or on your ornaments. Over time, with WC's that too will all be gone. You won't need to recycle the tank, if you go slow. From what I know, freshwater bacteria lives in waters up to salinity of 1.006-1.009. From there saltwater bacteria slowly takes over, as FW dies off. So, it will probably depend on your salinity. If you are on the low end brackish, you can likely go back to FW over a month, with just weekly water changes. I wouldn't go taking out all your gravel. Doing it slowly will also acclimate your mollies back to FW. If you are in the high end brackish, you may want to do WC's that only lower your salinity more slowly, to prevent your bacteria from crashing all at once.