12FT Pond Filtration Plank 1651mm Length - Complete Kit With Fittings12FT Pond Filtration Plank 1651mm Length Complete Kit With Fittings. This kit enables pipework going to your filtration equipment to be taken through the pond wall and not over the side so unsightly pipework is kept hidden below the water line. 2 x 1651mm boards which combine to give you a 4" diameter hole. 1 x 1651mm filtration plank with 1. 5" diameter hole. For use in conjunction with a 12' Octagonal Layzee Living walled pond. Whats included: x2