The 57 gram container of Seachem CoralCrete Epoxy Adhesive â Purple is a powerful two part epoxy putty that is designed to safely and securely adhere coral to rock formations, or to stabilize existing rock formations. The putty is ideal for working with large colonies of branching coral, large polyp coral and adhering plating coral to various rock surfaces. It can be used submerged or emerged and stays workable for 5 minutes before it starts to harden. The solution will cure within 24 hours. Completely safe for all inhabitants of your tank.