Kolognekoral
New member
Mike,
why Vertex went the way it did, I can't tell you, but I can explain the theories behind optimizing LED lighting for marine tanks.
the original idea behind optics was to increase the PAR of individual LEDs, in the theory that, when equally spread out across the heatsink, you would still get enough PAR over all areas of the tank. I've tried this and, yes, it can work fine, but the real question is, is this a better method. I don't think so.
Much of the reason this approach became so popular is the safety factor in calculating heatsink efficiency. (most of us had no idea of what was required and in the USA DIY was required due to the patent fight) By spreading out the idividual LEDs, one was maximizing the the heat distribution. Fact is, most of us are using over-engineered heatsink proportions.
Another reason for this approach is the wide lens of an LED (120° aprox). If the LEDs are spread about the heat sink, those at the edges will overshoot the tank. with clustering, this is no longer a problem.
When one doesn't invest in optics, one can increase the number of LEDs and gain more light and finer control.
Some statistics:
1) when the light passes through the optic it is bundled into a tighter angle/cone. This increases the PAR, especially at the top of the cone, nearest the LED. If this is too close to the water you will get a hot spot in the shallow parts of the tank. As the cone of light spreads, the PAR, of course drops through expansion of the beam and penetration of the water. Once it hits the sand, you will have about the same results as a clustered LED (sans optic). The disadvantage of the optics, in this case, is the tendency to create hot spots, as well as colour spots in the tanks itself. A compromise is to cluster 3-5 different coloured LEDs under a larger optic, but you still get a hot spot due to the optic. If you were to slice-up the levels of the tank and check the PAR, you would find a relatively fast drop off in PAR, due to the spread of the light. This strongly stratifies the light creating hot layers as the light cones meet. As this is an unnatural situation, I would expect corals to find it difficult to adapt to. I do think the aquarist can learn to controll tghis, however, it may be part of the reason some people have managed some intense burning with their fixtures.
2) when light passes through even the best quality optic, you loose at least 10% of the light. It is not focused into the optics beam. Without an optic you won't loose this light.
3)when light enters the water it is directly refracted to a tighter beam, about 10% tighter. When it hits the glass, depending on the angle, 80-90% is reflected back into the tank. For the Vertex Illumina, the test parameters were with the lamp 15cm/6" above the water on a 24" wide tank. The light reflection back into the tank is about 90%.
When comparing these figures we see that both approaches come out with similar results. Contrary to popular belief, an optic does not increase the final light product, it just changes its concentration at the exit point from the lens. This may be usefull for certain tank applications or a wasted effort for others.
As one say, two ways to skin the cat, the optics give an initially stronger beam, loose the same amount of light as a clustered configuration optic vs glass refraction/reflection. The clustered array gives a generally softer light distribution of well blended light. Optics tend to create hot spots and colour spots, depending on ohw high above the water they are hung.
As you can see, there are plus and minus to both approaches. I prefer the Vertex approach and my corals seem to as well. Also, the shimmer is more intense.
