In submersed form it is definitely a light loving plant indeed, got it in a wood dominant scape with about 5 kilos of Mopani and this still leaches tanines like crazy it's like my water rather looks like worst coffee ever color instead of tea after a week.. That already blocks a lot of light and this plant doesn't seem to love that very much, but it still is to early to say.. 🙂those flowers look awesome, looks like it'll block a lot of light out, will you be able to grow it flowering out the top without the leaves underneath going all dead looking?