I'm planning on building a new 4,000 gallon above ground pond and using
existing 2,000 gallon below ground pond as veggie filter/settling
tank/nursery. Looking for links and advice on construction techniques. New
pond will be 3 feet above ground and 2 feet below ground with landscape
brick retaining wall. Thanks for the help.

I'd start with the first site listed
here. Lots of info and links.

http://www.pondrushes.net/
and
http://www.geocities.com/bickal2000/pond.htm
and
http://www.fishpondinfo.com

k30a
and the watergardening labradors
http://www.geocities.com/watergarden...dors/home.html