U channel VS. heatsink for LEDs...

[Devaji108]

the build:
36 cree led's for a 75 gal LPS softie nem and a few SPS tank 48x 24x18

here's what i am thinking:
3x 42" channel
or
4/14" x35" heatsink

here are my question:
I believe 36 led if enough light yes?
would 35" heatsink fit 36 led with out over heating?
would 1' or 2" channel be better? (with that is)
anyone know where I can get a heatsink anodized?

any and all thoughts on the over all "best" heatsink would be great!
I am looking for a clean build as I have no canopy...

[lucidvtec]

i used u channel... heat sinks are way over kill....i put a fan on my setup when i was building it...it doesn't need it...i'm running 13 xpg;s and 13 xpe's barely warm to touch after being on 13hrs....

been running my setup for months now.....i used arctic silver and screws for mounting

i saw a diy setup done with heatsinks and it felt hotter than mine...i think the heatsinks retain the heat...i swear it seems like the u channel disapates the heat faster or better

[kcress]

U-channel works great. It's also about 1/5 the weight and 1/5 the cost.

I think you're way short on LEDs.

48" long x 24" wide = 1152sqin

1152sqin/16sqin/LED = 72LEDs

[der_wille_zur_macht]

LED count will depend on exact model, bin, drive current, optics, and other factors. I think you are a bit on the low side but not unreasonably so, given the intent to keep mostly lower-light stuff.

[jimnrose]

I'm using U channels and also feel they are more efficient as well as design flexible than commercial heat sinks (they are both heat sinks). Also the number of LED's depends on the water depth. Jim

[Devaji108]

yes i understand that both are heatsinks just did not know what else to call it.
i know a lot of ppl use the channel... do you guys wire for dimming? I would like to control the white and blue separate. for some reason I think the wiring would be easier on a heatsink.

was thinking of using XPg 2:1 cw to RB mount the fixture 2'-2 1/2 from the tank w/60% lenses . if you guys think I am on the low end of output. I would rather do more now and run the fixture at less output so I have the ability grow with my light.

maybe 48 leds would be better then. 14 on each channel using 4 channels.

[James77]

I used the U channel, and it worked beautifully. Wiring is no different or no more difficult than a full heatsink. If anything, it is easier being able to go up and over the U channel or ziptie the wires to it.

48 would work well on a 75 gallon. I had about 78 on my 120, and would go with about 60 on that( 6 inches wider) if I could do it over again.

[der_wille_zur_macht]

Keep in mind that Soundwave had 48 LEDs on his original 75g build, and they were rather poor LEDs by today's standards (mid-bin XR-E) with no optics. His tank wasn't outrageously bright but pretty much dead-on for the types of coral you are talking about. Given you will have optics, and are using more efficient and powerful LEDs, 36 is likely gonna be just fine. That said, if you want to go ahead with 48 I'm certainly not going to talk you out of it.

At 2+ feet up, I would be thinking about 40 degree optics instead of 60's.

[Devaji108]

ok sounds good guys I will use channel for the heat sink.
still not sure on the 36 or 48 led...about $100 difference. not sure what would be better to run 36 @ or around 90+% or 48 @ 55+%

how high are most ppl mounting there led setup above there tank?