LEDS for sps tank

[matthew660]

How many 3w Cree leds do I need for a 75g sps tank? And what color combination? If anyone with experience could help that would be great. I am currently running 48 3w Crees (24cool white & 24 royal blue).

 

[jbdreefs]

How do you have the leds arranged? If they are spread out evenly over the tank, 48 is probably not enough. If you have them more concentrated, then maybe. For instance, if your leds are mounted in a 40 x 12 inch square, centered over your tank (not as bright on the edges) I think that 48 would be plenty. Obviously, there would be less light on the edges of the tank. However, just remove the lenses from the left and right most LEDs and you will probably like it. There would be a 4" gap on the sides and a 3" gap on the front and back. Depending on the height you mount the lights, you may be just fine using optics on all he LEDs. Just my two cents...

The above configuration would give you one LED per 10 square inches. Compared to what I did, I think that would be enough. My configuration gave me a 1:6.67. I believe the general consensus is that Crees are better lights than what I used, which should compensate for the difference. Here is my build thread.

 

[matthew660]

I have them mounted on 4 6"x6" heatsinks evenly spaced along the length of the 4' tank with 12 leds per heatsink(6 royal blue & 6 Cool white). I was thinking I might need to add another 48 leds. I have a birdsnest, monti, frogspawn, hammer coral all of which seem to be happy and have been for about 3 months now, but I have some gsp that refuses to open in my tank but I can move them to my wifes stock biocube an they open within about 20mins. Any ideas?

JBDreefs;727539 wrote: How do you have the leds arranged? If they are spread out evenly over the tank, 48 is probably not enough. If you have them more concentrated, then maybe. For instance, if your leds are mounted in a 40 x 12 inch square, centered over your tank (not as bright on the edges) I think that 48 would be plenty. Obviously, there would be less light on the edges of the tank. However, just remove the lenses from the left and right most LEDs and you will probably like it. There would be a 4" gap on the sides and a 3" gap on the front and back. Depending on the height you mount the lights, you may be just fine using optics on all he LEDs. Just my two cents...

The above configuration would give you one LED per 10 square inches. Compared to what I did, I think that would be enough. My configuration gave me a 1:6.67. I believe the general consensus is that Crees are better lights than what I used, which should compensate for the difference. Here is my build thread.