Thorite

[Diomedes]

I have used waterplug in 20+ different rock structures and displays, but I never actually apply it underwater, if that is what you mean. It should be possible, considering waterplug can be used to seal very powerful leaks in certain structures. But it sets so quickly that doing it outside the tank really doesn't harm the rock or the corals if used to attach frag bases.
IMO Waterplug is superior to epoxies in many ways, especially when you learn to use it properly and efficiently. If you ever want to see a tank that has three rock columns completely bonded with Waterplug, check out Beecher Street Cafe in Crescent Beach, White Rock. The food is awesome as well.

Good Luck
Stephen
www.aqualibrium.org