Aquascape Black Silicone Sealant is used for sealing joints where liner attaches to the BioFalls snout and skimmer face plate. When installing a skimmer box or BioFalls, it is important to properly seal the liner to the filters. This prevents costly leaks in the system. Our fish-safe, black silicone is dark in color easy to use, allowing you to quickly make professional seals. The 10.1 oz. tube is to be used with a caulking gun for quick application. Aquascape is passionate about the products we produce, providing unique products, designs, and features that stand above the competition.