The Great LED Debate

I'll say this again as I have said it many times before...

According to manufacturers spec, most diodes will last 40,000-50,000 hours IF properly cooled, with regulated current. Running 12 hours per day, a properly powered and cooled diode will last over 11 years. Most drivers will not...but that is beside the point. When will the spectral shift occur? No one knows. It will happen just like it does with all other lighting. Once the spectral shift occurs, the diode is as effective as a 2 year old MH bulb. So your case of replacing MH lamps (and T5HO lamps) yearly is due to spectral shifts, not because the lamps die after such time. Average MH lamps will last 4 years, spectral shift or not. T5HO will last 3 years, needing changes every 8-10 months. So lets, for arguments sake, say that a single LED diode will have its spectral shift 1/4 way through it's spec'd life (2.85 years...call it 3). The cost of replacing 2 MH lamps yearly for 3 years comes to roughly $480. The cost of replacing every diode on your fixture after 3 years comes to...

Until LEDs have been field tested for years and data shows that these magical diodes don't shift, the "no bulb change" advantage is a moot point with me and many others.

 

This post is argument of the worst kind. All three of those statements are consistent with each other. It is not unusual for a person to say things in a different way at different times, or to accommodate a changing focus. Here, you treat what is at worst a slightly evolving position as what comes across as an attempt to personally discredit the debater.

On another note, I have a doctorate. That and $5 will barely get me coffee these days. Sanjay is a smart guy, but he deals in numbers and this debate is about empirical results. In the face of successful colorful tanks, a lot of people keep yelling about spectrum and other esoterica. I feel like I am being asked whether I should believe the experts, or my own lying eyes.

If those opposed to LEDs concede the point that they clearly do work and what were discussing is aesthetics, then I'll take another look and tell you whether I think MH or LED tanks look slightly better.

 

Actually there is no reason to believe they will experience a spectral shift. LEDs don't use phosphors like both T5 and MH and there is no filament. They are more likely to just get dimmer in time rather than shifting.


The color of an LED is a function of the material used to make the junction. There are two main flavors used in visible light LED junctions:

Indium gallium nitride (InGaN) is used to make up the blue, white, true green, and UV types.
Aluminum gallium indium phosphide (AlGaInP or AlInGaP) is used to make the red, yellow, and orange types.

 

I think you should try to talk to Sanjay face to face about this. You can do it at macna so that Greg and i can also be there

 

Gcarrol, none of the fixtures you listed would I consider a cutting edge product. Why quote an old test that used ways of testing traditional lighting (MH and t5) with fixtures that wouldn't compete with the ones Logan is referencing? Also, I haven't heard a response to Logans comments that the meter doesn't read led based light correctly which would further invalid your argument. This could e because I am on my phone though

 

Exactly, the spectral shift only occurs when the LEDs are not properly cooled, by fans, a heatsink, or both. The 50,000 hour rating for crees means that after running them for 12 hours a day for almost 12 years, they will drop 25% of their power, not even go out.

 

Does experience with metal halide really matter? The point is, I adapted new technology for my tank, as I saw the worth of using less power to achieve the same results. I have seen plenty of local tanks, and of course being a lighting guy, I ask a lot of questions about, you guessed it, lighting! And what I hear 99% of the time is pretty much this: "The corals look great, but I am always really worried when summer comes along, so I had to buy a chiller. On top of that, my power bill is through the roof!" Another guy I know cools his whole house to about 70 degrees, just to cool his tank. So I have seen plenty of metal halide systems in action, and always hear about the heat, and the power bill.

 

If your LEDs are properly cooled, which take nothing more than a slab of aluminum and some fans, they will last. Honestly, what if the metal halide ballast craps out after three years. Is the ballast going to last longer because it is powering metal halide bulbs? I think not! In fact, most of the drivers I use have mini heat sinks in them, on top of being cooled by fans whenever they are in use inside of the fixture housing. LEDs have been field tested for a few years now, and are starting to be widely adapted now because of their capabilities, and the fact that the prices are lower. Why wait 12 years to see if the LEDs are good? Keep them cool, and you will not have problems.

 

Yes it matters very much. IMO, you have no real concept of what MH nor T5 are capable of. It would be like me getting a Marineland LED unit and comparing it to my MH sytem and hailing that LED is no competition to MH. You statement about your MH and T5 knowledge has enlightened me as to why you are so passionate about LED and why you feel that it blows away MH and other forms of lighting.

I honestly don't think anything good will come out of this thread as you have shown that you are not in this thread to learn when you clearly have seriously limited knowledge of reef lighting as a whole. Sure you may know LED but I don't know if I'd qualify you as an expert in the field as you seem to completely disregard true scientific data becuase you seem to lack the understanding as to why it is the best form of lighting comparison.

The heat issue of MH is valid but not to the extremes that you have cited. On most occasions, system design changes can remedy the issues. My tank is running on 1400+ watts of light and I don't have a chiller and temp rise is less no more than 2 degree daily variation on my tank temps even in the summer.

 

1400watts+ is my point exactly. How big is your tank?