Lighting question

[AAE]

Hi all!  I was listening to Cory talk about his and Dean's efforts to measure PAR in a systematic way with different size aquariums.  He talked about the pattern of greater and lesser amounts of light energy in the tank from light source (e.g., corners, height of the tank).  I believe he said a black background can diminish the light energy (if that is the right term) by up to 20%.  He also discussed using 2 lights in parallel to aid filming (I believe he said he tunes the lights to a low level).  

I am planning a 60 inch long, 20 inch high and 24 inch deep medium light planted tank (with a black background).  His talk got me thinking about the following as I consider how to plant the tank:

1.  I assume that a 48 inch long light on a 60 inch long tank would result in less light on the sides of the tank.  I am thinking it could be reasonable to plant low light plants along the side and medium light plants below the light fixture.  I know I could use two 30 inch lights side by side to get more light into the side.  However, perhaps having darker sides would allow more variation in plants used?

2.  Since the black background should diminish the light energy the plants will use (I presume at the back of the tank), I am wondering if it would be good to have 2 light fixtures (set to a low level) in parallel to spread the light energy more evenly through the tank (back to front), for the purpose of plant growth and health.  

I would appreciate any thoughts on this. 

Thanks!

[Pepere]

I have the hinged glass lids on my tank and as such I run two lights on each tank, one over the back glass panel and one over the front.

having two lights you can place lower light plants under one that you keep dimmer….  Or in the case of a 48 inch light on a 60 inch long tank, put your low light plants on the ends…. Or you can have your low light plants in the understory shade from taller plants.

My thoughts on the black background is that it reflects less, light back in to the tank..

[AAE]

@Pepere, thank you for your input!  Very helpful!