Hi all. 1st time post couldn't see anything in searching.. What im looking at doing is covering a ceramic or pvc 75mm diameter half pipe with 3mm gravel. Its for a cave that blends in to my substrate ..in a tropical freshwater 4ft aquarium. My trouble being what glue to use on such a large surface area, as supa glue would be near impossible a task... Any assistance with glue types and brands or ideas on how to achieve this project that will be safe for the aquarium would be greatly appreciated. Thank you..