Eelgrass, Sago Pond weed, American Pond Weed, etc are all good. Think of the plants that have a lot of green mass underwater, those will utilize the most nutrients.

Some great ones, but I don't recommend them because they are invasive and can overtake a BOW quickly, but utilize a tremendous amount of nutrients are Curly Leaf Pondweed and Eurasian Watermilfoil.

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).