Herco Caulk Crack Filler - 12oz Tube - Clear Herco CCF Caulk Crack Filler for use in concrete, brick or block ponds. Fills gaps and seals leaks in new or old construction ponds. Cures quickly and retains elasticity under a wide range of conditions. Used with Herco PSC Primer and H-55 Coating (not included) to seal your pond.