Best to take the coral out of the water, dry the spot where the glue will go, then put back in the tank and attach where you want it with a little twist or two. The reason for the twist is that the glue will immediately skim over when it hits the water and the twisting action breaks the skim. Most people do have have any luck with mushrooms or ricordea and super glue as they tend to slime alot and the glue doesn't stick.