If there are springs in the bottom of the pond, the water will flow both ways, depending where the water pressure is the highest.

On if it will work or not, here is a company to call. Talk to them.

http://www.btlliners.com/

www.hoosierpondpros.com

[Linked Image from lh6.ggpht.com]
http://www.pondboss.com/subscribe.asp?c=4
3/4 to 1 1/4 ac pond LMB, SMB, PS, BG, RES, CC, YP, Bardello BG, (RBT & Blue Tilapia - seasonal).