If you are going to use Vallisneria you should read the good info in this link.
https://www.tfhmagazine.com/articles/aquatic-plants/vallisneriaAlso consider Vallisneria americana var.natans also called Vallisneria natans as noted in this thread.
https://forums.pondboss.com/ubbthreads.php?ubb=showflat&Number=555234#Post555234When planting I would plant some also in some shallow tubs to get it started; use just pond bottom sediment or garden dirt. Those in tubs are also easier to protect new plants from all herbivores. Once established in pans or tubs the dense growth can be transplanted to desired areas.
