Getting Figure Eights Tomorrow

[crackmonkey]

The fish store im getting them from keeps them in freshwater as do all my other local fish stores, should I keep them in freshwater and then gradually raise the salt level, can you wait till they're older before having to keep them in salt? The salt I have is Red Sea Salt, is that okay for Brackish fish?

Also, the Ph of the tank they're going in is 6.8 and Figure Eights need 8.0 or so im told, will they be okay in 6.8 until I get some crushed coral arognite for my external filter?

Thanks