royal blue 3W LED bulb intensity

likefish

New member
After much searching I have yet to be able to get a solid grasp on LED intensity.

I have a 24" deep tank with 18 3W royal blue (RB) LED bulbs by bridgelux. What I am trying to determine is how "hot" or "intense is the beam from each bulb with no reflectors.

Reason for the question is i am trying to determine what intensity to run them at. Are they generating PAR and if so at what intensity? LIttle, Alot, not enough, too much?

These lights are a suppliment to 4 ATI 48" T5 bulbs. Mixed reef, 120 gallons, 2' deep, 4' wide, 2' front to back. Lighting is mounted 10" above the water.

Questions:

1) Does a RB LED, 3W, at 100% power produce too intense a light at the top of the water column for SPS? and how much light is remaining at 24" of depth? Concerned about too much light for my LPS.

2) I have found that the beam from a diode is 120 deg with no lens. ANyone know if the light is evenly distributed throughout this 120 deg cone or is there a "hot spot" directly under the LED (and if so what would the diameter be at 12" and 24".

I feel as though i am grasping for sucess in the dark right now. LED's are powerful and i am concerned about to much light.


Thank you for the information and input!!!!
 

likefish

New member
Here is a picture of my tank. My design was to grow sps on the right side of the tank (area of higher light due to shallow water). I need to adjust my lighting to support this area which is 12" deep or shallower.

Concerned that i will burn my SPS with my blue LED.

2012-08-01_19-08-25_259.jpg
 

nemosworld

New member
what driver are you using for those less, bridgelux leds should not exceed 700ma
safe area being 680ma. that being said i would run them full power at 680ma with no optics and everything will be fine. you do lose some par with no secondary optic on them, not sure if they are any hot spots, but i guess that depends on how close you have them to each other, if they are in clusters, i think your par/intensity would go up, but if you have them in a linear design, then you should have no worries.
 

likefish

New member
Driver is a Maxwellen dimmable driver: Output current 680 mA (+/- 5%), i am running a potentiaometer at about 25% (just a guess)


LED's are 18 royal blues in a line spanning the 4' evenly spaced for coverage. Centered in the tank.

Can anyone quantify "low/high light", "should be enough", "about right"........

Or let me know what you are running for blues only, how many, how long, how high are they mounted and at what intensity.

Thank you for the reply! I cant seem to find any other posts like this out there. If you know of one please link!

Thanks again. The help is greatly appreciated!
 

likefish

New member
Let me try to re-ask the questions:

1) Is a 3W LED 10" over a tank going to emit a beam that is too high of a par anywhere within that beam? Tank is 24" deep.

2) If one LED emitts a par of X at 12" and there is another Led adjavcent to it with overlapping coverage is there a point within the cones of light that is two times X ? There are 18 LEDs' in a line overlapping ??? can it be too intense?

I am concerned that my blues at 100% would be too much light and cant quantify an answer.

There must be some LED gurus out there!

Help greatly appreciated!!!!
 

pwreef

New member
To answer your question in simpler terms, you need about 90-100 of those aquastyle LEDs to light your whole tank properly for SPS. So 18 are not really doing much, especially if you don't have lenses on them. I would say most of your light is from the T5s now. To know for sure what you need you have a PAR meter. Since your tank is empty, you will find that different corals you buy will come from different lighting and they may do well, or not at all, depending on many other factors. Good luck!
 

chris s

New member
You will be fine. Before I switched completely to led's I supplemented 2 XM 10k MH with 24 RB leds with no reflectors. This was on a 120 like your's. I ran them at 100% and had no burning even just below the surface. At 100% the RB just managed to offset the yellow look of the XM 10k's. The tank had a crisp white light with little to no blue look to it.

To answer your question, the further off the center axis you go the more the intensity drops off. So the first half of the output is where most of the intensity is concentrated. In your case the first 60 deg is the most intense. If my math is right. At 34" that's a circle about 40" across. That's a huge area. Without optics 18 leds over a 120 have little chance of burning coral unless you group them tightly together and have something directly underneath near the surface.

Reefledlights did a optic comparison on a 60 led fixture that measured 24"x8.5. 18 white 42 RB. At 24" with no optics they got 214 par. Your using 1/3 as many chips spread over twice the area, don't worry about it.
 

mcgyvr

New member
Questions:

1) Does a RB LED, 3W, at 100% power produce too intense a light at the top of the water column for SPS? and how much light is remaining at 24" of depth? Concerned about too much light for my LPS.

It could..
and it could be as little as 10-20% the par vs near the surface.
Optics HELP greatly in that respect.. you want them.

2) I have found that the beam from a diode is 120 deg with no lens. ANyone know if the light is evenly distributed throughout this 120 deg cone or is there a "hot spot" directly under the LED (and if so what would the diameter be at 12" and 24".

I feel as though i am grasping for sucess in the dark right now. LED's are powerful and i am concerned about to much light.

The datasheet for each LED will have a chart of the "typical spatial distribution" which will show what % of light is available from each angle.

And like said above.. Unless you only want coral in a small 12" x 12" area you need WAY more LED's to be worried. Not to mention when you build a light you should pick a dimmable driver. This not only allows you to fine tune the intensity as required but to also simulate "real" conditions (sunrise/sunset,etc..).
 

likefish

New member
Great answers! Thank you.

Just going to increase my power by a bit every few days until i get a color I like. and then call it good.

My SPS are goind to be in the top 24" of my tank. I designed my rockwork to allow this.

Bottom half of tank will allow for assorted softies and LPS.

thank you again for the details explanations!
 
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