To Peter I received your note and will make the same post. On Northern ponds siphon pipe are set four foot below water level and the main purpose is to drain the pond if needed not to maintain water level. Also minimum two 4 foot pvc weep collars backfilled with mason sand to trap clay wash.
If your main purpose of installig one is to drain the pond you can always use and above ground set up when needed.
good luck
