LED question

[lilrobb]

So,

let's assume I will be switching to LED in the very near future (trouble starts here) - and I would have a LARGE supply of LEDs (3W) for fairly cheap (as in, amount of chips is no concern).

I know how to wire them, and I know how to mount them - what I don't know is how many I will need on a 72x36x24 tank.
Is there any rule of thumb for chips per sqft?

Another concern;
I can get all sorts of driver cheap - is there any way to connect them to my Apex (maybe via the VDM module) and make sunrise/sunset work?
(I yet have to find a driver that doesn't use a control know but uses input voltage to adjust brightness - suggestions?)


Robb

 

[crewdawg1981]

I wanna know what you know Robb. My favorite price is "cheap"

 

[vanished88]

I would suggest 180-240 3w leds for that size tank (based upon what I have read). My tank is 72"x30"x24" and I am going with 240. I wanted to make sure I would have complete coverage with good par, and be able to run the leds at a low current.

 

[crew]

LED's can be placed as close together as you want as long as heating is taken care of. As for sunrise/sunset with the apex, you use the variable speed ports to ramp the voltage up slowly.

 

[lilrobb]

Vanished88;635675 wrote: I would suggest 180-240 3w leds for that size tank (based upon what I have read). My tank is 72"x30"x24" and I am going with 240. I wanted to make sure I would have complete coverage with good par, and be able to run the leds at a low current.

That's a low number going by the reefbuilders article, they suggest 56-60 per sqft - which would be roughly 970 on my tank...

 

[morganatlanta]

Before you invest that much get a par meter and check out the par in some of the various tanks that have LEDs.

970 LEDs, or 970 watts? 970 x 3 Watt LEDs would be insane.

 

[lilrobb]

Unless I overlooked it he doesn't state what wattage LEDs he is referring to:

“On deeper tanks over 24 inches, I like to add a mix of secondary optics to the LED array. I’ve observed that a relatively small number of secondary optics can provide enough extra light penetration while minimizing spotting and colored shadows,” he says. “It may take some trial and error, but I believe a good starting point is to cover 15 to 25 percent of the LEDs with a good secondary optic, and LED densities of 54 or even 60 LEDs a square foot may be required, at a nominal drive current.”

 

[vanished88]

LilRobb;635678 wrote: That's a low number going by the reefbuilders article, they suggest 56-60 per sqft - which would be roughly 970 on my tank...

56-60 3w leds per square foot is an ungodly high number. Just for reference, if you used aqua illumination sol units, they recommend 6 units for your tank placed 12 inches above the waterline. each unit contains 24 3w leds. thats a total of 144 leds. 970 leds would be equivalent to 40 AI sol units.....

 

[lilrobb]

As for the drivers, do I want PWM or DC dimmables?

 

[vanished88]

LilRobb;635719 wrote: As for the drivers, do I want PWM or DC dimmables?

depends on how you want to control them

DC dimmable if you plan on using reefkeeper/apex

 

[morganatlanta]

Can you borrow a couple AI fixtures from someone to use as a reference? They use 8 groups of 3 x 3W XP-Gs in W/RB/B, for 24 LEDs per fixture. If you are DIYing with CREE LEDs, I'd recommend following their design to get the right color balance and penetration while minimizing colored shadows. You could spread the groups around differently on your DIY to give more even overall coverage than you would get from the AI fixtures though. I imagine that you would need roughly the equivalent of 6 of them, maybe 9 at most, which would be roughly 150-220 LEDs, certainly not 970.


I've got my DIY LEDs running through a variable speed port on my Apex for sunrise/sunset. It was really easy to do.

 

[lilrobb]

So Morgan,

you did not need to use the VDM module for sunrise effects?

 

[lilrobb]

200 would make this entire project under $500!!!

 

[lilrobb]

Sure am, at that price all LED's will come with either 60, 30 or 15deg optics.

I need to correct my figure though, in order for full color control I need two more drivers - so make that under 600...

 

[vanished88]

wow thats cheap what kind of leds, heatsinks, and drivers are you using?

I spent $1000 in leds alone.....

 

[morganatlanta]

You are getting 200 CREE XP-G/Es for under $500? I can't believe I paid $6/ea for XREs just last fall.... Being an early adopter sometimes sucks...

Nope, you don't need a separate module. Just use the variable speed ports (V1/V2) (assuming you aren't using them to control pumps). Each channel takes one port. See the tutorial at ReefLEDLights.com.

 

[lilrobb]

Vanished88;635741 wrote: wow thats cheap what kind of leds, heatsinks, and drivers are you using?

I spent $1000 in leds alone.....

For that I would get 1000 LED's with optics.

3W LEDs - but that's as much as I can say right now.
Drivers are not finalized, heatsinks are cheap:

Edit: These are NOT CREE chips - maybe I should state that
<fieldset class="gc-fieldset">
<legend> Attached files </legend>

 

[vanished88]

Sounds like you came across a great deal. If you are able to give more information later please let me know, for those kind of prices I would be interested in doing an led setup for my refugium and my freshwater mbuna tank.

 

[lilrobb]

Let's say - I travel to China frequently...

 

[vanished88]

LilRobb;635755 wrote: Let's say - I travel to China frequently...

rofl that reminded me of last year when I went on a cruise and brought a suit case of cuban cigars. Customs was such a joke, they didnt check for anything....