Yep this is for the australian tank. Since I collect pretty much everything that goes in my tanks myself, including the fish and plants, I'm not 100% certain which val species I have.
One of them is a broad-leafed one, which, depending on the lighting conditions, develops very broad (20mm+) leaves, with a rusty red brown colour near the tips, and a deep green at the base. I suspect that its a local strain of V. spiralis, as it gets the long corkscrew shaped flower stems on it in summer. It produces runners with little baby plants on the ends. Unfortunately it tends to revert to a thinner leafed, greener phenotype when I transfer it to my tanks with artificial light. The dam it comes from has fairly soft, acidic water, (pH 6.4, GH 40 mg/L and KH 1-2) and I try to maintain my water at around pH 7 and KH 4, so that might also be factor in the development of the different growth form.
The other species might be V. nana. It only grows in shallow, high flow areas of the streams where I chase my fish. I haven't really tried growing it in a tank yet, so this will be a bit of an experiment. It has a big rhizome with an extensive root system that grows just below the surface of the substrate, with lots of idividual plants sprouting from the rhizome. I don't think it produces runners. It has much longer thinner leaves than the other species. The river it came from also has very soft, acidic water (pH 6.2, GH<20mg/L and KH about 1).
Maybe I'm worrying too much. Vals are about the only plants that I've had much experience with, and they seem to be petty easy to grow. I'll try them with the 40W tube on the tank (which works out to just 0.8W/gal) and see how they go. If they don't seem to be growing I'll have to invest in more lights.
