LED Layout Question

B

beolson25

New member
All,
I know this topic has been repeated a lot. I wanted to get opinions on my specific plan.

I have a 75 Gallon Tank(Standard size). I am planning 50 LEDs with the option to add about 5-10 LEDs in the future where needed(based on my driver specs). I am planning 20 Cool White and 30 Royal Blue CREE XT-E LEDs run at 1.05 Amps. I am planning to start without optics and may add them if I feel they are necessary(My fixture will only be 5-6 inches from the surface of the water due to being in a canopy). My drivers are dimmable so I can adjust color and intensity that way. I have the attached layout which is very generic and distributes the LEDs evenly. Please note that the attachment only shows half of the fixture but the plan is to have the halves mirror each other so if I get opinions on one side then I'll use the same on the other.

The excel document attached shows a 10" by 22" area for LEDs to be mounted. I have already accounted for 1" on each side not having any LEDs and the center brace has a 3 inch gap where no LEDs will be so please use the entire area shown in the layout document. In that sheet each little square represents 1" square on the heatsink. The larger squares where the LEDs are marked is because I plan to mount the LEDs in the middle of those 4 squares and I didn't have any easier way to represent that.

So ... my concern is ... If I have the 5 rows with RB, CW, RB, CW, RB ... Will there be any concern of the final product showing lines along the length of the tank? Meaning ... will there be visible blue streak along the back ... then visible white streak, then blue again ... etc ... ?? I don't suspect that will be an issue but I want to avoid having to move the LEDs since I am using a double sided thermal tape for mounting so if I have to move it I will have to clean and replace the thermal compound. The other option would be to somehow stagger the CW and RB in the same rows but I didn't see any obvious option for that ...


P.S. I understand that everyone will say I should introduce different colors to broaden the spectrum but I know what I like from that perspective and if I am unhappy I can always adjust the spectrum later by adding or changing out LEDs. So ... I am not all that interested in that discussion.


So ... I hope I stated my problem well and I can get some responses over the next several days. Thanks ahead of time.
 

Attachments

Last edited:
Adding a Heatsink Question

Adding a Heatsink Question

So ... I was looking over some other threads and I came up with another question. About Heat sink.

I purchased the heatsink in the link below:
http://www.ebay.com/itm/251790494165?_trksid=p2060778.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

I am planning on running the 50 total LEDs with a gap in the center for the brace about 3-4" wide ... So ... 25 LEDs on each side. Please keep in mind this will be in a canopy so there is not a lot of free air moving around. The drivers will be kept under the tank so they will not add any heat.

Do you think I will need fans for cooling with such a large heat sink? I'm thinking I might be able to get away with no fans.

If So ... Any ideas for where to place them? and how many? and what size?
 
For the front row you gave me an uneven ratio to work with, I had to put the extras somewhere and the front seemed like the best place. My logic behind disbursing the blue and white rather than to leave them in rows is to spread the light better for more evenly colored shadows.

I doubt you would have banding issues with no optics.
 
I don't see an issue with spacing, but the RB:CW:RB:CW:RB will give you bands and you will see it.

I have built Several fixtures, so a few bits of advice.

1. 5-6" will get covered in salt spray and splashes. I would use an acrylic shield.
2. I know you said your mind is made up on you LED choices, but I would urge you to consider NW over CW or at least a 50:50 mix of CW:NW. Look at Crees Data sheet for XPG and look at the benefit of NW over CW.
3. Don't let people talk you into reds or greens. They just look bad. Really bad.
 
ghellin,
Thanks for your response. I did already order the LEDs ... But I am aware that mixing in some Warm or Neutral Whites might help spectrum. I will purchase some extra LEDs if I don't like the way it looks.

As far as the Salt Spray ... Very good point. If you looked at the Heat Sink Question I linked the heat sink I bought from Ebay. It includes a splash shield. Besides that I also have glass Aqueon Versa-Tops. Currently my China LED fixtures are completely dry and have no salt creep so I am not too concerned ... I will continue to keep the covers on and also have the splash shield.

I won't get any red or green. I can't stand the way it looks currently which is why I am going back to blues and whites. Also, I'm using XT-E and I have seen the spectrum differences. I had an all RB and CW fisture on a JBJ 28 and I really liked the color so that is why I'm going with it again. But as I said above ... I may add or replace some of the CW with NW at some point. I am more concerned with how it looks to me than growing the perfect corals.


Can you suggest a layout you think would not cause columns? I'm having a hard time splitting the 15 Blues and 10 Whites evenly without using that layout. I don't want to group any whites together because then there would be a white spotlight effect ...

Any thoughts?
 
Ah ok totally skipped over your second post.... This my fixture I made for my 40B/46 bow front. The fixture is an old current 4 bulb T5 light I retrofitted a 34"x 6" heatsink into. I use two 2" fans blowing in one side and out the other. I have no heat issues with 28RB XT-E's @ 700mA, 7 CW XP-G's @ 1A, and 7 NW XP-Gs @ 1A.

 
Ghellin,
I assume you mean it does more harm than good due to the problems with salt and water buildup blocking the light from going directly into the tank ... Am I right?

I can't argue that too much but I have a fish I worry about becoming a jumper and I want to avoid evaporation since I still buy all of my R/O water. I try to keep it as clean as I can ...

If there is another negative impact I'd like to hear about it.


As far as your layout ... It looks good ... seems like those areas with primarily blues would be lacking white light though ...

I wonder if I asked a question where I can't be convinced out of my original design ... If that is the case it is obviously my fault ... I'm just not sure you will get even coloring if the LEDs are not distributed evenly ... :headwally:
 
beolson25 said:
Ghellin,
I assume you mean it does more harm than good due to the problems with salt and water buildup blocking the light from going directly into the tank ... Am I right?

I can't argue that too much but I have a fish I worry about becoming a jumper and I want to avoid evaporation since I still buy all of my R/O water. I try to keep it as clean as I can ...

If there is another negative impact I'd like to hear about it.


As far as your layout ... It looks good ... seems like those areas with primarily blues would be lacking white light though ...

I wonder if I asked a question where I can't be convinced out of my original design ... If that is the case it is obviously my fault ... I'm just not sure you will get even coloring if the LEDs are not distributed evenly ... :headwally:
Click to expand...
How about small clusters evenly spaced. Hmm 20 white 30 blue. So 10 clusters of 1 blue, 1 white and 10 of 2 blue one white? That would get you better blending. I'm not sure how you would lay that out though. Maybe three rows 7, 6, 7 with the row of 6 offset from the two 7s.

Not ideal, but not bad either. 40 blue to 20 white would be easier as it would mean all clusters are 2:1 blue to white. You can just dial back the blue to get the colour you want.
 
Avoiding the color discussion I don't see an issue with your layout as long as not using optics. The light will blend well, past about 2-4" below the water surface there won't be a noticeable band of color.

There have been a few very impressive tanks using only CW and RB one was tank of the month a while back. Water quality is key here as well as selecting corals that show well under a more limited spectrum.
 
beolson25 said:
Ghellin,
I assume you mean it does more harm than good due to the problems with salt and water buildup blocking the light from going directly into the tank ... Am I right?

I can't argue that too much but I have a fish I worry about becoming a jumper and I want to avoid evaporation since I still buy all of my R/O water. I try to keep it as clean as I can ...

If there is another negative impact I'd like to hear about it.


As far as your layout ... It looks good ... seems like those areas with primarily blues would be lacking white light though ...

I wonder if I asked a question where I can't be convinced out of my original design ... If that is the case it is obviously my fault ... I'm just not sure you will get even coloring if the LEDs are not distributed evenly ... :headwally:
Click to expand...

It also greatly reduces gas exchange which is something you very much want. Build a screen top, keep your fish and nothing to clean.
 
ghellin said:
It also greatly reduces gas exchange which is something you very much want. Build a screen top, keep your fish and nothing to clean.
Click to expand...

Well ... I have an open top refugium below and there is plenty of air exchange down there. But I see your point.

Thanks everyone for the comments so far.

I'm thinking I'll try it with the layout I presented ... AND ... If I find that I am having issues I can move them as needed.


I did just get my heat sink ... AND ... I am actually going to start another thread on that because I have questions specifically about that.

I do appreciate all of the input given here and will consider it as I continue to move forward with my build. Thanks again!
 
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