Gregcoyote
Aquarium Advice Addict
Anything that says it is "potable" can be used. That makes it safe for human and fish consumption. Make sure anything such as silicon sealers have no fungicides added...that can ruin your day. Inexpensive epoxy putty and gelled super glue that costs half what you pay to put a fish on the bottle and say it is for reefs is all available at the hardware store. I use a combination of the two when needed. Sometimes to grasp the plugs you have to use the putty to fashion a setting that has fingers that grabs the frag disk, like a stone in a ring.