rasta wrote:
i will be using a pottery (clay) urn laid on its side for a return to
the pond and need to drill a hole to accomodate a 1 inch bulkhead
fitting to tie in the dischage of the filter. don't have the first
idea how to go about doing this.

I've done up to 13mm in glazed pots with a masonry bit and a variable
speed drill. Slow and steady, with minimal vibration and you get there
in the end.

For a large pot, a 25mm bit should work fine, but it will cost you.
As an alternative, a pattern of smaller holes around the circumference
might work. The result will be rough, but servicable.

glen.