speaking of topsoil part my shallow end was left as "dirt" as my pond was built. We worked the dam end with a core and money got tight as it took more effort and depth than originally planned we wanted this end right and left a portion to "backwater" if this did not hold then we would attach that later as long as the dam was good. That said maybe this is where my higher nutrients are coming from. I had not thought that to be an issue at the time.
Dave
