Ah heteranthera... my favorate plant... Great setup man. I'm amazed how much depth it conveys. Hope I'm not stepping over my bounds here, but may I suggest that you reduce - even if it is fantastic - the HZ somewhat and add another stemplant? Maybe R rotundifolia. just to loosen it up abit. Personaly I'm not a big fan of the Nymphaea. Very impressive setup! It needs a background tho.