Aquascape® 54003 Economy Foam Gun Applicator. The Aquascape Economy Foam Gun Applicator is ideal for applying waterfall foam sealant in ponds, waterfalls, and other water features. Foam sealant is used to redirect water and fill gaps in waterfalls and streams. The economical applicator is ideal for DIY projects. Precise dispersion of foam makes it simple and easy to use. Designed to create an air- and moisture-tight seal between the gun and the can, the applicator provides maximum foam yield, and its efficient design minimizes waste during use. For use with Aquascape Professional Black Waterfall Foam.