LED lighting

The 4 shadows around a player is sort of what I'm talking about.

A better example would be here: 5http://www.reefcentral.com/forums/showpost.php?p=17467355&postcount=75

When he gets to the paper and you see the drop shadow effect. Optics for a hanging light are almost required. Both for appearance and to get the power you'll need ( at least for reefing, maybe not so much for our weeds ). I'll definitely be using them when/if I get there on the bigger tank. For the smaller tank, as it's all enclosed I don't see the point. Additionally, given that the cube is only 19" high I'll probably be a whopping 16" or less off the substrate at best and likely within 2" of the water surface. Too few LEDs and I'll have that multiple shadow effect. I don't know if more would help in that or just make it worse. Maybe a diamond diffuser plate like they put on flourescents? Of course then I'd probably lose the shimmer too which would be unfortunate.

I was looking online and found that I can drive 12-14 LEDs in series with my drivers. I have two drivers so I've got options. However, if I'm not trying to drive my LEDs at full amperage, and don't need independent color control, and instead opt for 300 mA I can run 4 strings in parallel at the same time. So now I've got an option for 48-56 LEDs on one driver with a practical limit of however many fit in the 9"x16" area inside the splash shield. I should be able to make this light up pretty evenly and still need to turn this down quite a bit.

But does that get me anything other than a stupid amount of LEDs in the hood? Do I get the shimmer effect or is that gone as I've evened out he lighting too much? Do I end up with so many shadows it's going to give me epileptic fits? I know I can get frosted optics which might also help diffuse the light a little bit, but I'd still like to keep the shimmer if possible.

-
S

 

Another idea...

Why not use a "tubular skylight," such as the Velux Sun Tunnel
http://suntunnelskylights.veluxusa.com/consumer/productinfo/rigid_tunnel/pitched_tmr/default.aspx

Or, for really high tech, why not a Parens Fiber Optic light system?
http://www.huvco.com/products.php?product=parans
California has great sun, and great tax incentives (not to mention the 30% federal tax credit). No bulbs...ever. Nothing beats pure sunlight.

As great as LEDs are, doesn't seem like we are trying to do this sometimes?

 

Can't take credit for the tubular skylight idea.... http://reefcentral.com/forums/showthread.php?t=1205844

Some creative Reef guys beat us to it. I remember reading about it a while back.... A guy was frustrated at the cost of MH lights, chillers, etc... so he tried the tubular skylight idea. I thought it was a brilliant solution. The thread is worth the read...

 

I thought of this a while back, but there's a general lack of consistent sun in the Northeast so it's not really an option. Plus the upstairs neighbors would probably be somewhat less than amused...

-
S

 

If you are going to use glass you need to take into account it will halve (quiet literally) the PAR you would have without one!!!

Therefore you can either put the glass (or other diffuser) sheet there and have the unit sat on top of the tank (2" as stated above) or have no sheet and raise it up 10" but achieve higher PAR.

What I am talking about are those open grid like mirrored diffusers. They don't do anything other than stop you seeing into the unit without trying to do so. No accidental glare if you know what I mean. They are open and not sealed. Just a basic silver grid. criss cross style and about 10mm (half an inch) in depth. Purely there to stop eyes from getting burnt unless that is the desired outcome in which case you can look up from directly below. lol

Before I put the optics in mine that was what I was going to use. Prior to the optics my unit was totally opne. Hung between 7" and 15" from the surface and had no problems but then I'm a sucker for having bare wires with electric current just above water

Unless your tank is splashing like mad it shouldn't ever be a problem if the hanging equipment/lighting mount are secure and not prone to failures.


On the shadowing question. I see what you mean now. However it is always very easy to see an effct like that with a still straight edge like he uses. Very hard to see when leaves are moving and are not straight edged. It may be happening but un-noticeable if ya know what I mean by that. lol

As for the colour separation I only have 1 colour so I can't comment on that. They're all 5500K or at least in the ball park of each other.


EDIT: What I've been calling a mirrored diffuser is actually called a 'louvre'. Learn something everyday. They look like this:



AC

 

I use the smaller grid ones for a cover on many of my tanks.

I've also been reading that the clear plastic diffuser panels that you can get at Home Depot seem to be able to remove the effect of multiple shadows and reduce a lot of the shimmer, but still allow for some caustic lighting effect, so this may be the way to go on that.

-
S

 

If you are aiming for efficiency I wouldn't put anything between the actual light or lense and the tank. You will reduce the PAR by half even with clear glass. Therefore you use more energy than you need to. If going the route of reducing energy use whilst maintaining the light then utilise it fully Check out the PAR readings in this thread with and without a glass panel:

http://www.omnima.co.uk/forums/index.php?showtopic=6

AC

 

If I wanted a LED set up for a 60cmx30x36,
Which would be better.
20w 32cm or a 20w 60cm?

 

that depends. its not just the length. it is the spread. I would suggest the 60 would be better as long as the LEDs aren't in a single line across that 60cm and as long as multiple rows aren't too close together

AC

 

Indeed it would Tom. That's what was great about the cheapy old polished reflectors compared to the expensive fixed ones. The cheapies were clipped onto the tube and you could angle them slightly outwards rather than both straight down. Useful on the majority of stock tank where 2 tubes were in the rear half of the canopy with a flap at the front

Amazes me why they never did this simple alteration in the luminaires over the years. They could surely judge the angle needed from the length of the unit (and probs therefore the tank length)

Even if they had slightly angled them it would've improve the spread.

AC

 

you sure love your metal poles Tom Are you not allowed to put holes in the ceiling and suspend lights?

Andy

 

The biocube has a plastic splash shield already. Given the sheer amount of overkill even a small 12 LED array would likely be able to provide at full power I'm not too concerned. From the thread I was reading, the diffuser wasn't really the problem in reducing the PAR. Just moving the PAR meter from above to below the water surface caused more PAR reduction than putting the diffuser in. The major difference in lighting seems have been been better color blending and reduction in shimmer.

-
S

 

That thread I linked to shows pictures of him taking the measurements. Even just below the water surface PAR is almost halved under the glass lid! However that is with his flouro not LED. Maybe LED is different



Taken from this thread:
http://www.omnima.co.uk/forums/index.php?showtopic=6

At the substrate (50cm tank) the readings were 102 with and 70 without.

Quite a difference and even with LEDs penetrative power and lower spill I would suspect a similar fate. Just using less power to get the initial 278 but still getting the circa half measure with the glass.

AC