Make sure you’re using quality adhesive products for this task. Saltwater can be highly corrosive, so you’ll need to use materials designed to withstand some of the toughest conditions. Tank builders often recommend using a gel-based superglue as well as a water-resistant epoxy putty. Using both together is crucial to creating a quality seal within the rock and raising your success rate.
In order to glue coral frags to rocks the right way, you’ll need to apply your glue and putty properly. First, make a ball of putty large enough to fill the gap in the live rock but small enough to limit the amount of excess left over. The putty will fill in any nooks and crevasses in the rock and create the seal. Apply glue to the plug, and stick the soft putty to it. Next, use more glue on top of the putty. Once you’ve completed these steps, press the plug into your desired position and let it cure.