What is the best way to get rid of weeds without chemicals?
Grass carp, maybe? It depends on the weeds.
Manual Removal, but again, it depends on the weeds. What kinds of weeds do you have in your pond?
Some weeds can break apart in to smaller pieces and start growing from that. This is where manual removal can make things sketchy.
Looks like sea weed at a lake.
John, once you know for sure what kind of plant you have, it will be easier to figure out the best way to manage it. Get some good, clear pictures of the plant, nice and close up. Then check out what types of vegetation grow in your area and compare. Or you can post pictures here and someone can help.