Need help with the spacing for 84 LEDs over a 90g.

[Jeff000]

Had been using 36 LEDs as supplement to my T5s but got 48 more LEDs for Christmas to rid myself of the T5s.... I think.

36 Cool whites XP-G
48 Royal Blues XR-E
7 ELN-60-48D Mean Well ELN-60-48D Dimmable Drivers
I like the blue look.

Anyways, the inside of my canopy is 48x17 3/4

I figure I will use a 44"x16" sheet of 1/4" aluminium to mount everything to, there will be several 1" holes drilled to keep the venting through the canopy. At this time I will not be adding any active cooling or extra fins, but if it heats up more then expected I will add 1/2"x1 1/4" angle aluminium to the top of the plate as fins, and if thats not enough add active cooling. Having so many LEDs I do not think I will need to drive them very hard.

I do not have any optics, when I ordered I didn't think I would need them, but now I am second guessing that. I can always add them later.

I have a 7x7 overflow in the one corner so I am avoiding that too.

How far from the edges of the tank can I be?
If I stay 3" away from the glass I will have an LED almost every 2" with the parts directly over my rocks being 1.5" (edge to edge, not center to center)

Am I trying to use too many LEDs? I only have softies right now, but do want some hard corals, I will wire so that I can give one side of the tank more intensity then the other kind of thing.

Thanks for any help. I wish I could figure out sketch up, might have to take a picture of my grid paper layout.

 

[der_wille_zur_macht]

Am I trying to use too many LEDs?

I vote yes. With that many, especially given a tank full of softies, I'd probably stay in the 400 mA range for drive current. You'll get awesome efficiency that low as a bonus. Typical currents with 96 LEDs on a 90g will probably fry all but the hardiest corals. Plus, I'm sure you'll overpower your plate heatsink at typical power levels.

Regarding optics - how high up is the array?

Don't get hung on spacing - start them 3 - 4" in from the edges and go evenly from there, or change densities over rock/overflows are you're suggesting. Ideally, if you end up staying without optics, I'd probably want them further than 3" from the glass, but given your very high count you're going to start running into implementation difficulties if you put them that close together.

 

[jimnrose]

I have 72 LED's for my 125g (72x24'17) mounted in 5 rows with LED's screwed to the aluminum on 4" centers and adjacent rows offset by 3" (checker board pattern). Mine are 4" above the water line. I have a 50% mix making it easier to distribute the color mix. I started with optics but found they were a disadvantage at 4" centers (spot light look @ 16" depth).

I used buckpucks (6 leds/driver) and set up the circuits on 3 power supplies (with timers) to produce earrly/late lighting; transition; mid day intensity. The earlt/late leds are at .5w each while the others are at 2.2w each.

Being close to the water line I had a corrosion problem (salt spray) and had to add acrylic top covers.
Jim

 

[Jeff000]

I vote yes. With that many, especially given a tank full of softies, I'd probably stay in the 400 mA range for drive current. You'll get awesome efficiency that low as a bonus. Typical currents with 96 LEDs on a 90g will probably fry all but the hardiest corals. Plus, I'm sure you'll overpower your plate heatsink at typical power levels.

Regarding optics - how high up is the array?

Don't get hung on spacing - start them 3 - 4" in from the edges and go evenly from there, or change densities over rock/overflows are you're suggesting. Ideally, if you end up staying without optics, I'd probably want them further than 3" from the glass, but given your very high count you're going to start running into implementation difficulties if you put them that close together.

I was hoping to be in the 350-400 mA range. So this is good to hear. I'll add some fins to the plate for good measure too, can't hurt.

How high, I knew I forgot to add something. It will be 9 1/2" between the water surface and the emitter.


The array will be PLC controlled. I am undecided if I will have the light start at one side of the tank and move to the other, but I will have a 3 stage on/off cycle to ease into the light.
I also have 8 red LEDs that I have been using as a night light for 10 minutes before and after the lights, and for the 10 minutes before I go to work (and I can turn them on with a push button when I want at other times too). Lots of stuff goes on in lights out. lol


Also with my meanwells do I need to open them up to adjust the internal trim pot thing?

 

[der_wille_zur_macht]

ELN-60-48's have two internal trimpots - one adjusts current, the other voltage. Since you want to operate in the constant current region, you want to leave the voltage trimpot (svr1) alone, and adjust the current trimpot (svr2) to get your desired current. You'll need to do this with a "full on" signal at the dimming wires (10v). You pretty much HAVE to do this, otherwise you're running at an unknown current, as they don't come preset to any particular value from the manufacturer.

 

[Jeff000]

Being close to the water line I had a corrosion problem (salt spray) and had to add acrylic top covers.
Jim

Right now I do not have any kind of sheild, but I think for the whole array I might pick something up. Thinking of doing 5 rows so would get 5 lengths of glass... but not sure the LEDs will all end up in nice rows, lol. And a solid sheet would close off my take to air exchange?

 

[Jeff000]

ELN-60-48's have two internal trimpots - one adjusts current, the other voltage. Since you want to operate in the constant current region, you want to leave the voltage trimpot (svr1) alone, and adjust the current trimpot (svr2) to get your desired current. You'll need to do this with a "full on" signal at the dimming wires (10v). You pretty much HAVE to do this, otherwise you're running at an unknown current, as they don't come preset to any particular value from the manufacturer.

I thought the dimming wires are what controlled everything?
So just slap my clamp meter on a wire and dial it in till it says 800mA or so and then use the dimming wires to drop it to ~400mA after?

 

[der_wille_zur_macht]

Right now I do not have any kind of sheild, but I think for the whole array I might pick something up. Thinking of doing 5 rows so would get 5 lengths of glass... but not sure the LEDs will all end up in nice rows, lol. And a solid sheet would close off my take to air exchange?

I'd use a singe large panel of glass or acrylic. Much better protection, and it can actually HELP cooling if you have even a tiiiiiny fan in there.

I thought the dimming wires are what controlled everything?
So just slap my clamp meter on a wire and dial it in till it says 800mA or so and then use the dimming wires to drop it to ~400mA after?

Basically the ELNs have two inputs that determine the output current - the pair of internal trimpots, and the dimming connection. Essentially the intent is that you'd use the internal trimpots to set your nominal or maximum current, and then use the dimming connection to dim down from there as required. In other words, the intention is that you'd use the internal trimpot to set your max, then use the dimming circuit to fade on and off, do other effects, or temporarily adjust intensity.

So, if you want to run at a max of 400mA, I'd set the internal trimpot to give 400mA output - though it may not go that low, so you might HAVE to do what you're suggesting and set it for a higher current then using the dimming circuit to reduce down to your target current.