Laying out my LEDS - opinions please

The time has come for the part of the DIY LED build everyone loves, laying out the diodes for the best coverage and mixture.

I have a couple of ideas and I see pros and cons for each. I would really like some opinions on what people like, what people don't like and WHY

So first the equipment
52 total diodes. I will be using the center 36"( or so) of 48" heatsink over my 90 gallon tank. My heatsink is made up of 2" wide aluminum channel. I will either run 3 or 4 lengths giving a 6" or 8" wide heatsink

LEDs as follows

24 RB = Cree XTE RB
8 NW = Cree XTE 4500K
4 WW = Cree XTE 3250K
6 B = Cree XPE Blue (465-485nm)
6 V = Exotic Hyper Violet 430nm
4 T = Exotic Turquoise

Option 1) 4 clusters of 13 leds. Each cluster would be approx 7.5" at its widest and about spread about 7" front to back. , giving about 2" spacing between the clusters. I would use 4 2" alum channel for heatsink. this is based loosely on the AI Hydra 52 layout...same shape, different colors



Pros: diodes grouped tighter should provide better mixing
Cons: possible spot lighting with strong par and light in 4 areas of tank
possible issue with Heatsink. To complete this layout the center of the 5 rows would be positioned where 2 of the aluminum channels meet. Not sure if this would be an issue


Option 2
6 groups of diodes, again spread over 36" 4 groups of 9 in the middle, 1 group of 8 on each end. each cluster would be about 4.5" across and would use 3 2" aluminum channels for heat sink



Pros: alignment on heatsinks front to back easy, Spreads the diodes more uniformly along the length of the tank, spreads colored leds more along the length

Cons: Maybe spreading colors too far in order to mix well. No good way to surround colors could have a chance of mix issues.


So now I ask everyone their opinions. I appreciate any and all feedback on the layouts especially those with WHY the like/dislike.

The less are purchased so I won't be changing the make up of the array just the layout and spacing left to be determined.

Thanks in advance

 

Fixed diagrams of layouts in original post

 

I don't think you would have to worry about spotlighting with either arrangement and both are good choices.

With that said, I like the first one. You will have a lot of light in that center which means the edges would be a great place for corals with less demanding light needs. It will also allow you to skip some space for your center brace, if you have one, and not waste any light hitting that.

 

Thanks. No Center Brace. That was my choice of the 2 as well, just wasn't sure was gonna get enough coverage length wise without really spreading out the clusters and negating the benefit of the cluster

 

What does this look like, exactly?

Don't skimp here; keeping the diodes cool under operation is of the utmost important.

If they run too warm, it doesn't matter how good your layout is, they won't last.

 

I like the first layout too. It gives you areas of high par to place your demanding corals and shaded areas for others.

 

I am using this heatsink on my current build whichI am re doing , for multiple reasons. It is currently 4 aluminum channels, 2" wide and 1/2" deep. They run 48" long and originally had 18 leds on each.
I have not had any heat issues , the heatainks remain cool to the touch, and I also have 2 120mm fans blowing across the heatsinks.

Currently the channels are seperated by about 1.5" , but for the new layout I plan to push them together, and are connected at the ends by another aluminum channel.

I will try to post a pic of the current build later today

 

Personally I'd go for option 2 as this would give you a even spread of light. Option 1 is and would be prone to spotlighting which personally I hate seeing and well if you mount the LED's in a "spotlight" fashion then that is exactly what you are going to get... Some people like that effect but that's usually because they spent thousands on a manufactured LED fixture and they are going to say they like it regardless if they truly do or not.

One thing that hasn't been mentioned is which optics you plan on using, this can easily help with proper diffusion of the different colours.
Optics are an obviously an important step as it will determine the overall height of the fixture, but for instance if you went with 80 degree optics on all the LED's you'd probably end up mounting 12 inches off the water and not have any trouble with diffusing the specific/dominate colours with option 2.

Basically when it comes down to adjusting the fixture height you'll know then whether or not you need to remove some optics/lens from either WW or NW as these will be much harder to "blend/diffuse" with the surrounding light. This might even allow you to mount the fixture closer to the water which means a higher par (if needed)!!

I again say option 2 is your best bet but it's just my personal opinion.

 

Awesome, thanks. This is exactly what I am looking for.
I will be using 80 degree optics and the fixture will be in a canopy approx 7 inchs off the water.

I am still trying to decide what to use or if I should use a splash shield. I assume yes but still working out the details

 

I would, especially if you are going to go 7 inches off the water. My splash shield is about 9.25 '' off the water and it still gets splashed.