Has anyone done spotlights effects with LEDs

[sfsuphysics]

I've seen some Japanese inspired tanks use various spotlights (halides usually however), but I'm wondering if anyone has done this with LEDs. I don't mean a single fixture (photon cannon, kessil array, etc) over a nano tank. I mean a cluster of LEDs that are specific for one particular coral/rock of a tank.

Most every LED build I've seen so far involved pretty much a linear or planar array of LEDs, basically lighting the entire tank. Heck even some of the actual spotlight LEDs (e.g. the "Photon Cannon") have been placed over a tank such that they try to light the whole tank with them. Being as I'm going to have 24 square feet of tank to light, of which most will be empty and I'm not interesting in helping any algae (nuisance or coraline) grow, I'd like to explore the idea of lighting only corals, and not the tank.

Whether it's one particular large structure with SPS on it or an isolated island of zoanthids far away from other rocks. Really curious about what has been done as far as keeping stuff alive. Replacing X watts with Y XP-G Crees really doesn't do me any good, I really would like to know how much light a coral needs.

Is my best bet to grab a PAR meter and mess around with values at a particular location? Or is there any rules of thumb? While I know the first thought would work, however it would require building arrays of various sizes, and testing various places individually (not to mention different LEDs would give different values which might not be terribly accurate). However I'm hoping that someone can say "yeah with a cool white XP-G with 40° optics 6 inches above a tank you can keep zoanthids going good that are 18inch deep" (but inside I'm not really anticipating this response... just hoping)

[kcress]

I certainly will be going that route. I have no interest in a uniformly lit tank. Too boring for my tastes. No mystery.

My build will also have two beams of sunlight so my LEDs will have to be non-planer to surround those projection cones.

You will probably need a par meter but one could probably estimate closely enough what the spot PAR will be to "get by".

Certainly you could keep your zoas in a beam of light! I'd use the starting point rule-of-thumb of about 18insq/LED. So something like a 12" circle would call for about:
6^2 x pi / 18 = 6 LEDs. Maybe three white(2CW and a NW) and three or four RB

Hopefully you could mount them up and lens them to all point at the same circular area. Perhaps using some sort of heatsink like the one I did on my fixture so you could actually point all the beams into a 12" circle. I actually did one that was for six LEDs and allowed pointing them all. I can't find my picture of it. It's actually sitting next to me so I could take a pic if needed.

[sfsuphysics]

Thanks for the reply, nice to know someone else is going this way as well.

18 in² per LED though? That's something like a 2.5 inch radius circle. Need to see how tight a beam you can make with optics. assuming 24" above the bottom of the tank that'd be 12° optics... or larger optics with more LEDs.

I'll initially have a couple of halides over the tank, just so the old stuff doesn't get too stressed while I'm fiddling around with testing.

Did see a couple of the Kessil fixtures this weekend too, so there's a fall back option if I want a compact design multi-emitter LED. Although ideally I'd want whites and blues on separate channels.

[Raven1645]

I'm not sure if this is what you're asking but you could also make a regular fixture with, say, 48 leds to light the complete tank without spotlights.
Then you have 120 degree beams on all of them, and you put 60 degree lenses on the ones where you want the spotlight.

[T Diddy]

Originally Posted by Raven1645

I'm not sure if this is what you're asking but you could also make a regular fixture with, say, 48 leds to light the complete tank without spotlights.
Then you have 120 degree beams on all of them, and you put 60 degree lenses on the ones where you want the spotlight.

good idea Raven

I considered the spotlight thing , but decided against it because relocating corals/frags/spotlights might be difficult. Neat idea though

[kcress]

Yeah, that would work. You could then add more LEDs later if desired.

Alternatively if you make small units of six or eight LEDs you can always move them individually to accommodate any moves of your coral.

[frankpayne32]

This definitely interests me as well. When I upgrade (eventually) to a really large tank I plan on doing this.

[sfsuphysics]

Originally Posted by Raven1645

I'm not sure if this is what you're asking but you could also make a regular fixture with, say, 48 leds to light the complete tank without spotlights.
Then you have 120 degree beams on all of them, and you put 60 degree lenses on the ones where you want the spotlight.

Not exactly what I was thinking about. Mind is going along the lines of 60% of the tank has no rocks or corals on it, why do I want to spend money lighting the whole thing, I want to spend money lighting corals, and that's it. Don't get me wrong I'll have a few wide angle white or something spaced about to give illumination to the whole tank so its not completely dark, but the less light on the ground and sides, the less coraline that grows there. Plus if I had some corals that grow a little too aggressively (zoanthid's come to mind as they mat out) having a single spotlight that defines where I want them to grow might help restrict them from going too far from where I put them.

Originally Posted by kcress

Alternatively if you make small units of six or eight LEDs you can always move them individually to accommodate any moves of your coral.

Kind of the direction I was aiming at. Those little tri-LED pucks that you see in the AI units made me think that direction. The key is to have a flexible enough connector (that you can remove via a plug) so that if I do want/need to move them it'll be possible (cat5 comes to mind, but I'm worried about connector points, and being as its not really meant to carry power I am worried what could happen). Also having a mounting system such that I could move them around easily will be key, considering it'll temporary house a couple lumenarc reflectors with halides in them

[marspeed]

i am planing on doing a spot lite type setup as soon as i get free time on the cnc lathe this is just my first render i have since added mounting holes and chamfered all edges also a pocket for the LEDs and holes for a splash shield

more pictures in my photo album

[sfsuphysics]

Is that heat sink for a single LED? Or one of those multiemitter chips, looks pretty beefy for a single LED.

Don't have any ability to CnC like some people around here so I'll be sticking with off the shelf type components, already got a 12 LED setup on an anemone tank from home depot U channel that's bolted together with a computer fan. However while the anemones have absolutely been kept alive not quite happy with the spacing on the LEDs I chose. (it was a first time attempt with Crees)

[marspeed]

should hold a 30 mm three up or three 10 mm stars overall size is around 2 1/4 " long and 1 3/4" diameter
i can still make changes, still up in the air as to a mounting bracket ?
led heat sink small.pdf




Marc

[kcress]

marspeed; Can you turn the cooling fins 90 degrees so they are running in the correct direction? That! Would be cool(er).

sfsuphysics; BuckPucks running on 24VDC are good for about 6 LEDs. That would allow you to use about any connector safely and without fear as you'd only have low voltage about. It would also allow you to plug and unplug your individual packages, live, without issues. They're also small so you could include them on each constellation.

[marspeed]

kcress
90 degrees would be cool(er)
will give it a try

[kcress]

Definitely. You always want the fins to be vertical if you can manage it. That's what's so sad about the big heatsinks being used, they're being used in the worst possible orientation.

It probably makes the part you're machining about 10x harder though..

[sfsuphysics]

Hmm, didn't even think about buck pucks, as they tend to be quite pricy if the number needed increases (however safety factor increases ).

That said do you have a part number? Dimable? Or is that an external feature?

[marspeed]

Kcress

yes it does make it harder but not impossible on a cnc lathe with a 16 position tool turret
i made an assortment of those big heat sinks some with pockets for electronics's and pockets for LEDs but scraped them all i am trying to keep this heat sink on one machine start to finish, this way i can make as many as i need
the vertical fins are the right way to do it, so may as well do it right

[kcress]

Originally Posted by sfsuphysics

Hmm, didn't even think about buck pucks, as they tend to be quite pricy if the number needed increases (however safety factor increases ).

That said do you have a part number? Dimable? Or is that an external feature?

Off-hand I don't know what the BP part numbers are but I think there are about 4 species. Something like 350mA and 700mA both dimming and non-dimming. The dimming is pretty straight forward. Just a pot if you want individual BP adjustment. Or you can drive them with some external signal.

[kcress]

Originally Posted by marspeed

Kcress

yes it does make it harder but not impossible on a cnc lathe with a 16 position tool turret
i made an assortment of those big heat sinks some with pockets for electronics's and pockets for LEDs but scraped them all i am trying to keep this heat sink on one machine start to finish, this way i can make as many as i need
the vertical fins are the right way to do it, so may as well do it right

I look forward to what you come up with!

[sfsuphysics]

Originally Posted by kcress

Off-hand I don't know what the BP part numbers are but I think there are about 4 species. Something like 350mA and 700mA both dimming and non-dimming. The dimming is pretty straight forward. Just a pot if you want individual BP adjustment. Or you can drive them with some external signal.

Ok sounds good, I search around from there. It'll probably be a month or more before I get around to making a prototype, but I kind of want to get the tank/room/electrical/support/etc built before I have the lights over it