Freshwater to saltwater conversion

[ivnurse77]

I have a 220 gal tank with no gravel and 1 large piece of African sinking rootwood.It houses a large redtail cat which I might have sold.
Can I convert to a salt tank by just adding the salt or do I have to discard the water and start fresh? It used to be salt.
I have 150 pounds crushed Seaflor bottom material in storage.
I also have a 75 gallon reef so filtration could be switched over immediately.

 

[Brenden]

I would empty the tank, clean it. Purchase a RO/DI unit if you dont already have one. And then refill it with the new RO/DI saltwater. If your using any of the same filteration from your FW tank clean that as well. Also your filteration for your 75 probable isnt large enough to be used succesfully on a 220.