LED Optics Selection?

[reeferdale]

Hi all,
I need to order optics for my LED rig and I could use some advice/input from the LED experts. Here is what I have:
Tank: 72" L x 36" W x 24" H
I am using six 18" x 10" heatsinks. Each sink has 42 LEDs spread evenly. I have 132 CW and 120 RB (Cree XP LEDs)
I will have 4.5" of space between the sinks from side to side and 5.25 of space between the sinks from front to back.
With this in mind, I am debating between 40, 55 or 80 degree optics. I can hang the fixture anywhere from 6" to 18" over the tank.
This is a mixed reef, heavy on SPS (acro, monti) many chalices, and assorted zoas, shrooms, plates, brains and frogspwan coral.
I was originally leaning towards using 65 degree for the whites and 55 for the blues.
My main concern is I don't want to spill a lot of light out of the tank, and I would like to be able to have really high PAR. I am afraid of spotlighting if I use all 40 degree optics. Since these are dimmable, I can control the white and blues to dial back the intensity. Initially the blues will be run around 800 mA and the whites around 650 - 700 mA
I would like to use all the same degree optics, but I can mix them up if it would be beneficial. Anyone that has experimented with optics that could lend some advice or an opinion I would appreciate their input.
Thanks
Dale

 

[CJO]

Assuming you are using Cree's or other high-efficiency LEDs, that's a lot of light! That's more than double the amount I have per square foot of surface area on my tank.

As far as optics go, that's the beauty of LEDs. You can use tighter optics where you need higher PAR for one of your corals (or clam, anemone, etc.) or to reach the bottom of the tank and wider ones were you are more concerned about blending colors. Optics are cheap. I would buy quite a few of each and swap them out until you get exactly what you want.

CJ

 

[reeferdale]

Assuming you are using Cree's or other high-efficiency LEDs, that's a lot of light! That's more than double the amount I have per square foot of surface area on my tank.

As far as optics go, that's the beauty of LEDs. You can use tighter optics where you need higher PAR for one of your corals (or clam, anemone, etc.) or to reach the bottom of the tank and wider ones were you are more concerned about blending colors. Optics are cheap. I would buy quite a few of each and swap them out until you get exactly what you want.
CJ

thank CJ, I think that is the way for me to go. I am going with no Optics until I get all my livestock transferred over and in place. Then I will add optics where I need and at the degree I need.

When you need 250+ lenses, they aren't that cheap anymore ;o)

 

[Troylee]

With that many LEDs I would use 70 or 80 degree optics myself... 70's have the highest par out of all iirc... I used 80 on mine and was happy with them... I could grow sps in the sand on a 24" tall tank without any issue.. One issue I did have was my chalices where bleaching unless in total shade... Hth

 

[bui]

I wouldn't mix optics if I were you. It kind of making sense at first but it create unexpect hot spot (area of strong light where multiple light cross). For your setup I would use a wider spread since you aren't that far from the surface of the tank and you dont growth too many sps, even if you do...it would be more likely at the top. Use a protractor to kind figure how your light will spread work. Make sure to check the length and wide spread. BTw, by your spec...that could easily grow sps anywhere in the tank.

 

[CJO]

I wouldn't mix optics if I were you. It kind of making sense at first but it create unexpect hot spot (area of strong light where multiple light cross). For your setup I would use a wider spread since you aren't that far from the surface of the tank and you dont growth too many sps, even if you do...it would be more likely at the top. Use a protractor to kind figure how your light will spread work. Make sure to check the length and wide spread. BTw, by your spec...that could easily grow sps anywhere in the tank.

You can get hot spots whether or not you mix optics. I've had mixed optics for over 1-1/2 years without a problem. Also, figuring out the angles can only help so much due to the refraction of the water.

CJ