LED: More intensity or lower fixture?

[glweek]

Assuming spread and color blending are equal, is there an advantage to having a fixture mounted higher above tank running a high intensity, than same fixture mounted lower with a lower intensity?

I would think if spread and blending are equal that lowering the light and running it at a lower intensity would be better: less light overflow and the unit runs cooler.

thaughts?

 

[mcarroll]

You're totally on the right track with your thinking, but "better" along the lines you defined depends on the light fixture design.

With the correct design, the lights hang where you want them, spill no light and run at optimum power.

Uusally this implies DIY, but not in all cases. Depends on the tank.

Take my DIY gu10 bulb rig for example:

• Perfect for any 12" wide tank from 10 gallon to 55 gallon.
• They hang at 12" from the tank - reduces risk to LED's from splashing and eases tank chores.
• They don't even light up the tank glass, let alone the room the tank is in.
• They have great intensity the whole length of the tank.
• Thanks to a good design (I stole the basic design from here - so should you), they are able to use very strong lenses compared to most LED fixtures you find, which reduces power requirements.

By contrast, if you put almost any commercial fixture over one of those rectangular tanks, from 30-50% of the light isn't even going to make it into the tank, you will have little to no choice on mounting height and more power-usage to do the same job (as measured by a light meter).

 

[Triggreef]

Depends if it's going to cover the area you need it to if you lowered it.

 

[kmog]

I may be wrong, but I'm pretty sure there is a minimum distance for the LEDs spectrums to mix regardless of how high it is over the tank I think they mix at the same rate. I don't know how much this affects corals, but with plants it makes a noticeable difference.