they are a medium low to high light plant, i have them in 10g tanks with 2 spiral compact bulbs about 15 watts and they stay red. they can get 18" with enough light and ferts. they will take a long time to get this big to,
most sites say all swords are medium light when there not really. i have the red rubin in the same 10g tank 15 watts and its red and growing out red to.