Pond and Stone sealant makes quick work of building and maintaining stacked stone for waterfalls and spillways. Easily fill gaps between stones so water goes where you direct it and creates a permanent bond that can be broken if needed. Expandable black foam also has insulating properties and could be used to mount lights and other equipment used around waterfalls, water gardens and fountains. It adheres to all surfaces and is moisture cured so it can be used underwater. The black color fades into the background of installations but could be painted if needed.