许多哈希迭代：每次都附加盐？

I have used unsalted md5/sha1 for long time, but as this method isn't really secure (and is getting even less secure as time goes by) I decided to switch to a salted sha512. Furthermore I want to slow the generation of the hash down by using many iterations (e.g. 100).I have used unsalted md5/sha1 for long time, bu