O.C. Nano display tank

[Ron99]

+1 on Eugene's analysis of the Nano Customs Par38 bulbs. It's a bit of clever marketing on the part of Nano Customs to quote total energy consumption rather then the actual wattage of the LEDs. Any light system will have energy losses so a 250W MH looses some at the ballast and is drawing more than 250W of electricity to drive the bulb at 250W. They have 15W of LED lighting in their bulb and use 40 degree optics to get higher PAR and penetration but in a smaller footprint. The 60 degree optics in the OC lights give a bit wider coverage but a bit lower penetration and PAR.

So for LED output count the number of emitters and multiply by the wattage they're driven at. To further complicate things some light fixtures drive 3W bulbs at 2W etc. so you aren't getting the full 3 watts of power. The whole LED thing is pretty complicated right now with many manufacturers trying different things in terms of how they drive LEDs and what LEDs are used and what optics if any. There is some hype and some BS out there but also some very good products.

For a top of the line it's probably the AI units right now for larger arrays as they use the best Cree emitters with optics and put out lots of PAR. The PAR38 spots are also excellent for smaller tanks or spotlighting. You can also use a larger number of them for the bigger tanks and that will work too but you probably need at least one spotlight for each square foot or so of tank.

It's a complicated right now as there are many options to work with and it is difficult to make direct comparisons with existing technologies like MH because of the wide variability in LED implementation.