In keeping with my design principle to prefer systems with less ongoing cost and maintenance, an LED lighting system was a natural fit. While LEDs cost more up-front than other lighting systems, the reduced power usage (both from the reduced wattage needed to drive the light, and the obviation of a power-hungry chiller to remove the waste heat generated by a metal halide system) and the emitter longevity justify the greater initial expense. Also, with LEDs that can dim to zero, and a variety of different colors available and separately controllable, an LED system would allow me fine control over the lighting color and intensity to optimize for coral growth and attractive illumintaion.

I decided to build my own fixtures, so I could maximize the customizability of the lighting color and intensity, and to ensure overlapping color coverage everywhere in the tank. Rather than using a miminal number of emitters operating at full capacity, and therefore creating islands of color in the tank, I opted to use a large number of emitters spread eveny around the surface of the tank, all operating at reduced power. Doing so for eight different channels of color allows me to model changing color temperatures over the course of a day.

Once I determined to model changing daylight colors, I also decided to model changing angles of incidence by mounting two of the fixtures at opposing ends of the tank, tilted inwards towards the center. By ramping the intensity of the Eastern fixture early in the day, and the Western later, the coral livestock will experience something akin to a more natural daylight cycle (the effect this has on their phototropism is something I am eager to see).

Among the four fixtures (two 24" fixtures mounted at opposing ends, and two 48" fixtures mounted lengthwise), there are:

  • 84× Luxeon ES 5000K neutral white emitters
  • 42× Luxeon ES 2700K warm white emitters
  • 28× Exotic 400-405nm (violet) emitters
  • 28× SemiLED 415-420nm (indigo) emitters
  • 10× Luxeon M 440-450nm (royal blue) emitters
  • 28× Luxeon ES 440-450nm (royal blue) emitters
  • 42× Luxeon ES 470-480nm (cool blue) emitters
  • 28× Luxeon ES 495-505nm (cyan) emitters
  • 28× Luxeon ES 660-670nm (deep red) emitters

The system for driving these emitters includes:

  • 34× Mean Well LDD-1000H drivers
  • 8× Mean Well LDD-700H drivers
  • 7× Custom breakout PCBs for Mean Well drivers
  • 3× Mean Well SE-600-48 power supplies