Aluminum U channel for LED's?

E

EnderG60

Plumbing Engineer
Im currently running 3x400w radium 20k halides along with 2x80w T5 ati blue plus's, and 2x80w T5 daylights(forget which one) on my 300g peninsula with the T5's running down both long sides of the tank.

Ive decided to swap out my T5 actinics for LED's since I want more pop from the corals. Im pretty sure Im going to go with a 48 bridgelux kit from aquastyle but I need a heat sink.

I would like to do a straight swap and remove the 5' T5's and replace them with 5' LED strips. My plan was to use 1"x1" Aluminum U channel but Im not 100% sure that one 5' length will be acquitted cooling for 24 LED's, and more so where I can order it.

So my questions are, what size should I get, what thickness/gauge and where should i get it?
 
I have used rectangle aluminum tubing before. I was able to get scraps from a local door maker for cheap. They were a lot thicker than the ones I could find at the store (I think the thickness was somewhere around 1/4"). It worked great. The width was 5.5" and the length was 48". I had 12 10W LED's on them, forgot the spacing between the LED's. It run cool and I tried the setup with 18 10W LED's and it got a little warm but adding two fans fixed the problem. I'm not sure what you would need for c-channel, thought I would share my experience to give you some ideas.
 
It depends a lot on how you are running the setup. With active cooling it works about as good as any other heatsink. The main disadvantage of using it for a heatsink is that it isn't as good passively. Heatsinks are all about surface area. Purposely built heatsinks max out surface area in order to run passively. You give that up by adapting something. But computer fans are cheap and easy to deal with (and relatively quiet), so the disadvantage isn't all that bad.

It also depends on how hard you push the LEDs. Over my sump I have two 24" strips with 4 Cree neutral whites each that run at 700ma. The strips are fully exposed to air, but cooled passively. It doesn't get warm at all. But then, over the main tank I have two 48" strips with 10 Cree and Luxeon royals blues each. They are enclosed but fan-cooled. When the fans are on they are mildly warm. When the fans are off they get a bit hot, but not enough to cause concern.


You should be able to get it at Lowes or Home Depot.
 
It will be passive cooling since the hood is ventilated. I have no clue how they will be run since its a kit and Im not going to bother doing the math to figure it out.

Local home depots do not carry aluminum U channel.
 
I also remember seeing someone who used some kind of extruded framing for the heat sink since it had more fins/surface area but cant figure out what it was.
 
EnderG60 said:
Local home depots do not carry aluminum U channel.
Click to expand...

Try looking in the lumber section. It is often sold as edging for sheets of plywood. Here in Ottawa, that's where you'd find it.

On the other hand, Lowes keeps it in the hardware/fasteners section.
 
All of my local Home Depots and lowes carry aluminum c channel. It is in the hardware section where you can buy steel rods, threaded rods, and flat bar.

As for the extruded aluminum, I am using some from 80/20. You can find it on amazon or their ebay store. I use the 25mm three sided t-slot. It has worked well for me in the past and I am using for another build right now. I really like all of their connector options and the fact that you can hide the wiring in the slot to keep a really clean installation.

Don't rule out the active cooling, you can try it without a fan and check the temperature. It doesn't take a lot of air movement to make a big difference in cooling. But if it is in a canopy without any air movement I think it will get too warm for my comfort (you will have to decide for yourself) My previous setup was over my tank without any enclosure and it was fine without a fan running leds at 2.5" on center spacing, at about 600ma each. But I had them dimmed slightly with a potentiometer. A simple solution is a 5" 120v fan from radio shack on a timer that runs the same time your lights do.
 
Khemul said:
With active cooling it works about as good as any other heatsink. The main disadvantage of using it for a heatsink is that it isn't as good passively. Heatsinks are all about surface area.
Click to expand...

Forced or natural convection doesn't matter.. Its NOT about as good as any other heatsink.. As you said it all about surface area.. A uchannel does NOT have near the same surface area as a proper finned/pin,etc.. heatsink.
 
mcgyvr said:
NO WAY can you run 48 LEDs on a 5ft aluminum U channel..
They will overheat/short life..
Click to expand...

I think he said 24 leds per 5 foot section in the OP. That is the same as my setup at 2.5" spacing for each led. I really think it comes down to how hard he is driving the leds. I would never say "no way" i am sure there are plenty of ways to make that work. If he is running them at 300ma i bet the c channel would be fine with passive cooling alone. If he is driving them harder i think he would still be fine by adding a fan. There are too many variables unanswered to make that declaration. The only way to know for sure is to get all the information, or build the thing and then measure the temperature.
 
wilkerschnepf said:
I think he said 24 leds per 5 foot section in the OP. That is the same as my setup at 2.5" spacing for each led. I really think it comes down to how hard he is driving the leds. I would never say "no way" i am sure there are plenty of ways to make that work. If he is running them at 300ma i bet the c channel would be fine with passive cooling alone. If he is driving them harder i think he would still be fine by adding a fan. There are too many variables unanswered to make that declaration. The only way to know for sure is to get all the information, or build the thing and then measure the temperature.
Click to expand...

ok 24 is better.. Thats "doable"..

When details are left out (and I'm too lazy to request more details like in this case) I always assume worst case...:twitch:
 
Many people have run LEDs on U-channel just fine if using single LEDs. It's ok if they get warm/hot as long as you can put your finger near the LED without pain your heatsink is fine and running at 700 is nothing. Keep them a few inches apart though.

Better yet run active by getting 1" square rod instead of U-channel from hardware store "same cost as U channel $15 for 8 feet" and search on favorite action site for projector fan "$10". This is same as a computer fan but enclosed and goes on the end of the square rod and blows air to the other side. Works way better than usual heatsinks /fan combo because 100% of air goes past LEDs and takes up less room. This is how I run mine and stays cool and takes up way less room. Additional bonus, I'm also able to use 3-ups instead of singles because of the active cooling inside the 1" square rods.
 
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square tube wont work as well since it will trap hot air inside and Id rather not deal with putting a fan on it. The hood already has very quiet ventilation.

Those makersLED heat sinks are really nice but way too expensive and way to wide. I just need a single row of LED's.
 
Its for actinics, I just want color. Im not looking to drive the hell out of them.

And if a $20 item and yield the same results as a $200 item why would you spend $200?

That heat sink actually looks perfect for what I need. Thanks!

EDIT: looks like the smaller 1.8" width has taller fins Ill go with that. $80 for two nice heat sinks isnt too bad.
 
if passive cooling the U-channel works better than those very thin fined 1.8" heatsinks because of the thicker sides on U-channel but if your running active then yes those heatsinks will work well.
 
If you don't mind spending the time you should rummage through your local scrap yards. I got lucky and picked up about 25 feet of 1/8" thick 1 1/4" U-channel for $17 ish.
 
EnderG60 said:
Its for actinics, I just want color. Im not looking to drive the hell out of them.
Click to expand...
The problem is the fact you have 3 x 400 MH bulbs over the tank, I would question how much actinic you actually will get out of them if they're run at relatively low power (i.e. 350mA). Unless they're mostly going to be on after the halides are off you might be surprised at how much you don't even notice them.
 
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