The colour of light

[bogusmove]

I've heard that light towards the blue end of the spectrum will encourage upwards growth and the red end more outwards growth, or I could easily have that the wrong way round, I forget... but there doesn't seem to be much knowlege lying around on the subject, does anyone know anything about this sort of stuff and if it is possible and practical to alter aquarium plant characteristics in an even partially predictable fashion by changing tubes? Just curious....

 

[Magnus]

You have it reversed, bogusmove. Blue spectrum -> short and compact plants. Red spectrum - long and leggy plants. But the amount of light is much more important to plants. If you have high light, plants will grow short and compact as well, and vice versa. I usually shoot for higher lighting and full spectrum bulbs.
I haven't really experiment with what you are talking about, but I'm sure someone else has.