depth light relation

[scubaD]

How does depth relate to lighting needs? Is there a serious difference between 24.5" and 29" depth ? Does a measly 4.5" make that big of a difference? I know this was mentioned in my aquarium thread, I was just hoping to get a broader perspective.

Thanks,
David

 

[smcnally]

29" is a pretty deep tank. If you plan on keeping SPS down low in the tank you will need stong lighting. I don't know an actual table to go by, but that is a pretty deep tank.

 

[joefitz]

Depth is an extremely important factor. Light has a hard time going through water, which is why it gets pretty dark pretty quickly when you dive in the ocean. In terms of our tanks, I'd say it has two primary impacts:

1) The higher the light source, the more spread you will get. In other words, it will cover a greater area.
2) The more depth the light has to travel, the less light will penetrate to reach your corals.

I do believe the height difference you reference could make an impact on a coral's growth and coloration. I've heard many of our most successful reefkeepers reference how moving some of their corals just a few inches made a tremendous impact on either their growth rate, coloration or overall health.

 

[Kiah]

Yes i think it might make a significant difference depending on the corals you want to keep. That 4.5 " adds over 18% more depth to the tank.
The Inverse Square Law of Intensity states that light intensity falls off as the square of the distance from the light. So if you double the distance from the light you have reduced the intensity to 1/4 of the original value. This assumes it travels through a perfect medium.

You have to consider light lost out the sides of the tank, light reflected from the water surface, light absorbed by particles in the water, etc.

 

[~Flighty~]

I have a really hard time reaching things 24 inches down in my tank which is the main reason I wouldn't want it deeper. You can always keep lower light stuff in the bottom half.