I'm new here, I hate to hijack a thread but it seems all questions have been answered for the OP.
As for the media, it's a sand and gravel filter. It does a ton of bio!!!! and takes very good care of the fines! I see this site has a pond forum, I'll post some pics of my setup. Till then if your interested in the filter, here is complete right up on the filter http://www.koiphen.com/forums/showthread.php?t=36550