Question About Used Red Dry Rock

[Tuxeedourchin]

Hi everyone, I recently purchased some used rock that was left to completely dry out. Some of the pieces beak easily and are completely red with white patches. I was wondering what kind of rock this is and if it is safe to use in my reef tank as I have never seen rock that is completely red like this, even on the inside. Thank you for any feedback.

 

[Saltyreef]

The pieces that break really easy are likely very old and the red is just dried algae.

Should be good to go unless copper was used with them.

 

[prokhk]

Some rocks are coated to look like they have coraline algae, or it might just be dead coraline if it came from an established system. Either way I think it should be safe to use if its been fully dried out to kill anything living on it as long as it is aragonite reef rock, which it looks like to me. If there is dead stuff on it, it will cause an ammonia spike as the stuff decays in the tank, but once that is past, it will be like any other rock.