If your area in TN gets ice cover or frequent winter frosts water hyacinth will not survive in the pond over winter. I think it requires a minimum concentration of iron in the water for good growth. In a small 1/8 ac pond you should be able to remove enough plants regularly during the summer to keep it from overtaking the pond. With the hyacinth growing well in the pond water should be pretty clear and very little filamentous algae.
