I have slow leaking, vertical crack in ceramic fountain. Can Flex-Paste be applied successfully to portion of crack that still is under water?

Hi there Howard, many people have had success using Flex Paste on fountain repairs. It adheres well to ceramic and is designed to work underwater. Please note that Flex Paste has not been tested as safe for use around plants and animals. For these applications, we'd recommend Flex Seal Liquid. Be sure the surface is clean of any dirt, oil, grease, or algae beforehand. Feel free to message us at Humans@FlexSealProducts.com for more cool tips and tricks. Have a Flextacular day!