newbee Boi-filter question

Hello all,
I've been reading here for weeks and learned much from all of you and my little
250 gallon pond is doing great. Thanks! I just picked up the remainder of my
stone today and I'm planning on moving my bio-filter back about a foot and left
about a foot. I'll then add an extension to my liner using liner tape and
rebuild the water falls that lead to my stream. I'm thinking of draining the
bio-filter before moving it and I need to know if an hour or two with the
filter empty will cause damage to the filter. And what way should I prep the
liner before using the liner tape? And iare there any other concers that I may
be overlooking?
Thanks again to all,
Pat
(the newbee in Philly)