No, the old rock will not grow back if there is no other live rock in the tank. The old rock will grow new coralline algae if you add some new live rock. I would not use the rock in a freshwater tank. The rock can grow some algae, but not much if there's no other live rock in the tank.
RockinAR - what's happened ?
You were giving good advise to members, and now you're upset about mods deleting posts.
Why are you posting these silly reply's, when it's clear that you have something positive that you could be doing instead.
Like helping members here with their questions.
This is not necessary at all.
Mods do not enjoy having to delete posts - this I can assure you.
I take offense to anyone "calling" another person a nazi.
Your participation on this board is always appreciated, but you'll need to tone down the personal attacks on members and moderators.
Anyone is welcome on this board - providing they adhere to a few simple rules.
Rules of online etiquette.
Not acting like a jerk to others.
Please change your signature at once.
That's uncalled for and very rude my friend.
It's pretty simple - shape up buddy.
It's your call.
Otherwise - you will be banned.