Hello. I'm interested in purchasing a freshwater Atlantic stingray from rmkoonaquaticpets.com. Now I know they can live in freshwater but it is not reccomended, so I would like to convert my tank into brackish water. How would I go about doing that? Also, would it be best to do so before or after I get my stingray (would placing him in brackish water effect him since he has been in freshwater from the seller?) thanks!!