Crispatula has leaves that undulate and are USUALLY narrower than retrospiralis when grown submersed. I can't tell them apart when grown emersed except when flowered. The spathe will show spots in retrospiralis and lines with crispatula.
No such luck in my present house. The front porch provides so much overhang that most sunlight is cut off, and a tree gets any sunlight that might make it past the overhang. I am ordering some 96 watt CF kits to get the best light I can on my 75 gallon.
I've had the same experience here. I've never been able to replicate the growth that pure sunlight give using artificial lights (including MH). That was one of Claus' comments as well when we toured FAN. He was jealous of the Florida sun as it is not as intense in Denmark.