Dan:

There are a few different "pondweeds". If they are of the genus Potamogeton, then the treatment is the same. If they are a different "pondweed" then the treatment may vary.

Go here, TAMU Aquaplant look at the different pictures of the "pondweeds" and let us know what one it is.

As for how many bass to remove, if you want to start over remove every one you catch. By leaning any in there, they can eat the small ones that you stock. The problem with that is if there are any hook shy bass in there, you won't catch them.

Since the pond is so small, find someone in your area that is a licensed aquatic herbicide applicator and have them Rotenone the pond. That will push the reset button and you can start from scratch fish wise. You have to have a license to purchase Rotenone.

www.hoosierpondpros.com

[Linked Image from lh6.ggpht.com]
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3/4 to 1 1/4 ac pond LMB, SMB, PS, BG, RES, CC, YP, Bardello BG, (RBT & Blue Tilapia - seasonal).