first it is the epmd liner i drilled holes in the wood.then i filled the pond to near the holes and let it sit for a day to settle out the liner i then used a drill bit for wood -paddle type flat then sharp and pointy on sides and center. i used a file to sharpen it more i then center the bit ad cut it by hand. you want a smoth cut that is smaller then the bulkhead. that way when you force it in it has room to move and creates a good seal.........selling the pond for 100 no filter droping rays untill jr is older and easyersoggysandwich;1696529; said:nice pond, im hopping to build one just like that. just a few questions for ya: how did you cut the holes in the liner for the bulk heads. and what size sump is that