Xref: kermit rec.ponds:146899

Although many people have specific areas for a veg filter, you don't need
one. The goal of a veggie filter is to have plants convert the waste in the
water into plant matter, before the algae can. The entire pond can be an veg
filter, if you can put the plants in areas where they won't turn into a koi
salad bar.

Almost any aquatic plant can be a veg filter plant, but the faster growing
plants are more efficient, which is why water hyacinth are so popular.

Sameer