I used the flat blade drill bit (1 1/8") to cut the holes in the 4" conduit. I imagine it would be the same as a spade bit. No issues at all.
Also, Rainman told me to rough up the plastic with sandpaper prior to sinking them in order to get algae to grow on it. I took a round wire brush drill bit and went all over the conduit with it. It scratched it up fairly well.

Last edited by SetterGuy; 05/10/15 03:44 PM.
9 yr old pond, 1 ac, 15' deep.
RES, YP, GS, FHM (no longer), HBG (going away), SMB, and HSB (only one seen in 5 yrs) Restocked HSB (2020) Have seen one of these.
I think that's about all I should put in my little pond.
Otter attack in 2023