L.E.D. vs HALIDE/T5/VHO

[OceanicCorals-Ian-]

Lets use this thread to carry out conversation on test results, opinions, and pro's and con's of L.E.D. lighting for Reef aquariums.

[viperfish]

How many watts per LED bulb is needed to grow SPS coral? Our benchmark for MH or T5 was wattage, how does this compare to LED? Is PAR the only reference available? If someone said they were runnung a 400W 14K MH bulb, you would know it would be awesome for SPS, this doesn't seem to exist in LED. All I hear is brand (mostly Cree) number of bulbs, and number of watts per bulb.

[sphelps]

While LEDs are looking more promising these days my main issue with them is the complexity and reliability. Not too much information out there regarding long term experience and performance. The only fixture that had been out for a while was the solarus but everyone I've heard of using one has had some kind of issue with them relating to either the drivers or LED arrays. In both cases servicing them isn't exactly easy. Other fixtures may be better but their popularity and presence isn't high enough to provide much experience. They also only come with a 1 year warranty which is complete garbage for a fixture that is suppose to last 10 years. Others may disagree but as an engineer in a manufacturing company I know exactly how warranty life is determined and limiting warranty to one year for a such a product is pretty big red flag.

I prefer to spend money on a quality fixture that not only looks good but works all the time. I can't justify spending more up front for a fixture that doesn't look as good, may require constant attention and maintenance and might not even last as long as suggested. Despite the potential energy savings the chance of spending less in the end isn't exactly that good which defeats the purpose IMO.

For now I think the LEDs belong to the DIY electronic guys who can easily fix there own work or build it better with quality parts and those with nano and smaller tanks where the upfront cost is less.

[Ron99]

Originally Posted by medhatreefguy

How many watts per LED bulb is needed to grow SPS coral? Our benchmark for MH or T5 was wattage, how does this compare to LED? Is PAR the only reference available? If someone said they were runnung a 400W 14K MH bulb, you would know it would be awesome for SPS, this doesn't seem to exist in LED. All I hear is brand (mostly Cree) number of bulbs, and number of watts per bulb.

It's not so much a watts per gallon type thing with LEDs as it more depends on how you set up the array. how many LEDs, what optics, how are they spaced. You can set them up to have high or low PAR depending on what you do and your budget.

Originally Posted by sphelps

While LEDs are looking more promising these days my main issue with them is the complexity and reliability. Not too much information out there regarding long term experience and performance. The only fixture that had been out for a while was the solarus but everyone I've heard of using one has had some kind of issue with them relating to either the drivers or LED arrays. In both cases servicing them isn't exactly easy. Other fixtures may be better but their popularity and presence isn't high enough to provide much experience. They also only come with a 1 year warranty which is complete garbage for a fixture that is suppose to last 10 years. Others may disagree but as an engineer in a manufacturing company I know exactly how warranty life is determined and limiting warranty to one year for a such a product is pretty big red flag.

I prefer to spend money on a quality fixture that not only looks good but works all the time. I can't justify spending more up front for a fixture that doesn't look as good, may require constant attention and maintenance and might not even last as long as suggested. Despite the potential energy savings the chance of spending less in the end isn't exactly that good which defeats the purpose IMO.

For now I think the LEDs belong to the DIY electronic guys who can easily fix there own work or build it better with quality parts and those with nano and smaller tanks where the upfront cost is less.

The Solaris fixtures were really poorly built. They had flawed power supplies and no heatsinks so LEDs overheated and burned out. They really weren't designed well. There are some good systems such as the AI ones but also many others that make compromises that reduce output etc.

It's really not hard to design a decent LED system that will be properly cooled and durable. But the costs are still a bit high so if you want a decent LED fixture you have t pay for it. There's no free lunch. Longevity should not be an issue if it is designed well as LEDs are well understood and their lifespan and degradation properties are well known. LEDs have been around since the early 1960s. Ones with enough power for more intense lighting started to appear about 9 or 10 years ago. The technology still has room to grow in terms of output and efficiency etc. so it will only get better.

[sphelps]

Yes I would agree the solaris fixtures where not built that great but there are still very few other fixtures that promise better results. The AI are the better looking fixtures as far as quality goes but to me the module design lacks the style I prefer to see in a fixture for open top tanks and the warranty still suggests a lack of faith in the reliability of the product.

As for LED reliability and lifespan I would strongly disagree. Yes they have been around for a long time but they are new to the hobby and the environment they will be exposed to. They will run hotter and in high humidity and also be exposed to the salty corrosive atmosphere. This will impact the lifespan of the LEDs just like it does for all other types of lights we use. Metal Halides for example are rated for 5 years before a 30% drop in standard applications but over time we have discovered that they only last one year in the hobby application. A similar result will no doubt be discovered with LEDs over time. A friend of mine also pointed out the other day that a lot of cars these days run LED tail lights as manufactures made similar promises about long life and reliability but you still often see multiple burnt out LEDs in taillights on still fairly new vehicles. At least if a regular tail light burns out it's a simple and cheap fix while the LED style simply is not.

An LED by itself is no doubt a reliable light source, however combining multiple arrays into hundreds of LEDs greatly increases the chance of failure and the fix isn't the same as simply changing a bulb.

[OceanicCorals-Eugene-]

Originally Posted by sphelps

Yes I would agree the solaris fixtures where not built that great but there are still very few other fixtures that promise better results. The AI are the better looking fixtures as far as quality goes but to me the module design lacks the style I prefer to see in a fixture for open top tanks and the warranty still suggests a lack of faith in the reliability of the product.

As for LED reliability and lifespan I would strongly disagree. Yes they have been around for a long time but they are new to the hobby and the environment they will be exposed to. They will run hotter and in high humidity and also be exposed to the salty corrosive atmosphere. This will impact the lifespan of the LEDs just like it does for all other types of lights we use. Metal Halides for example are rated for 5 years before a 30% drop in standard applications but over time we have discovered that they only last one year in the hobby application. A similar result will no doubt be discovered with LEDs over time. A friend of mine also pointed out the other day that a lot of cars these days run LED tail lights as manufactures made similar promises about long life and reliability but you still often see multiple burnt out LEDs in taillights on still fairly new vehicles. At least if a regular tail light burns out it's a simple and cheap fix while the LED style simply is not.

An LED by itself is no doubt a reliable light source, however combining multiple arrays into hundreds of LEDs greatly increases the chance of failure and the fix isn't the same as simply changing a bulb.

Its true that MH are rated at 5 years before a 30% drop in standard application, that is if the standard application was not to care about the total PAR values which is often what MH bulbs are used for (parking lots and etc.). The requirement for high PAR alone is what determines how long a MH bulb can be used for in the SW hobby and not so much the environment its been run at. The humidity and salty environment would effect the longevity by a very small amount as the intensity/color shift happens inside the bulb and not outside and a MH bulb is enclosed.

The same would apply for the LEDs except with LEDs heat becomes a great cause of failure on the emitters, most high power LEDs nowadays are rated to run at a constant temperature of 50C to 80C before damage to the emitters occur and most well designed fixtures with proper heatsinks and cooling run the emitters near 40C if not a tad higher. Just for reference the spotlights we carry run at roughly 48-50C without fans and thats 9 bulbs closely package together in a 6" heatsink.

With the car scenario, the LEDs are being put through conditions much more harsh than seen above our reef tanks, they have no heatsinks, no cooling, and have to put up with absorbing the shock and vibrations from the car moving, and I'll agree that we might not get the rated 50,000hrs our of the emitters but it'll be pretty close to it, for a couple simple reasons. LEDs through there lifespan doesnt have much color shift if any at all as theres no gases and no burning seen in the MH bulbs. The intensity will drop but if the emitters are used in the suggested range of specs by the manufacture it should drop to that % claimed by the manufactures.

[Ron99]

Eugene is correct. Unless you are running them right above your water without a splash shield then salt creep and corrosion should not be a big problem. There was one guy in the candlepower forums IIRC that posted a picture of an emitter he had been running over a salt water tank for a long time and it was covered in salt and corrosion but it still lit up.

Heat is really the enemy of LEDs. Like any lighting system it all depends on how it's designed and put together. If it is designed well and has adequate cooling you can expect the advertised life out of the LEDs. If it is not well cooled you can expect the LEDs to degrade faster. But LEDs themselves have been used on myriad different types of equipment in all sorts of environments so I would still argue that their reliability is well understood.

As Eugene pointed out the LEDs are best run at less than 80 degrees. The lower the better. I haven't measured the temperature of my heatsink exactly but what I can do is put my finger in one of the holes on top of the fixture and touch the heatsink. After running for several hours it feels just barely warm to the touch so it can't be above 40 degrees. I may add a temperature sensor hooked up to the Arduino when I get to that point.

As for cars, which ones seem unreliable? I have heard of some issues on Cadillacs but Hondas and Audis seem pretty reliable from my understanding. Again, Eugene is correct that the stresses on automotive components are far higher with greater temperature shifts and shocks and bumps and vibrations etc. Not generally a problem for aquariums.

So I think your criticism of LEDs could apply to T5s or MHs as well as there are good reliable systems and poorly built and unreliable systems. Doesn't matter what the technology is. Part of the problem you mention about difficulty in repairs is that in order to save on manufacturing costs the LED emitters are set up on modules in many systems and if one LED goes down the whole module has to be replaced as it is usually not simple to replace a single emitter once its on the PCB. I do give kudos to Maxspect as each of their LEDs is on a discrete star PCB and can be replaced individually if need be. Not so with the AI or several others where you have 3 to 6 emitters on one PCB. So again, depending on the design of the system, the fix could be as simple as replacing one emitter or having to replace an entire module. But replacing a module should not be more difficult or more onerous then replacing a ballast in a T5 fixture.

[sphelps]

Kind of my point guys. LEDs are rated for 10 years before a 30% drop in intensity occurs just like halides are rated for 5 years. So yeah halides only last a year before par is too low so how long will the LEDs last? It would seem obvious and fair to say they won't last the full tens years before requiring replacement.

Also yes all lights have failures which was also my point but the bulbs can easily be replaced while LEDs cannot be easily replaced. Based on the design of the fixtures I've seen it appears that once the LEDs fail or become too worn the fixture is basically trash unless you have the skills to fix it which in my mind isn't fair to assume we all do. In addition the shear number of LEDs is much higher than other alternatives so the chance of failure is greater.

Like I said looking more promising these days but it's too early to say too much about the reliability and lifespan of LED fixtures which is why I wouldn't recommend the option to most people. Enough said.

[Ron99]

The difference between LEDs and Halides and T5s etc. is that LEDs spectrum does not shift as they degrade. They simply lose output. With MH and florescent lights the spectrum shifts to undesirable wavelengths which compounds the loss of PAR. LEDs should last longer because they will only lose some output but not shift in spectrum. So 6+ years is a reasonable estimate for LEDs.

The added difficulty of changing LEDs will only be an issue if their lifespan is far less than what is estimated and I guess that's the crux of the argument. You either think they will last or you believe they won't. I suppose only time will tell.

[sphelps]

I'd agree that six years would be a reasonable estimate at this time. That being said with the current design of LED fixtures the energy savings will likely never give a payback if you have to essentially replace the fixture every 6 years. That's without my concerns of premature failure which seems fairly likely with what I've seen with current fixtures on the market and the lack of a decent warranty period on newer fixtures.

On the topic of par vs spectrum I don't believe you're correct, just because the spectrum of the bulb changes doesn't mean the par will also change. Certain halide bulb and ballast combinations will last far past the year mark in terms of par while spectrum is a separate issue.
http://reefkeeping.com/issues/2007-04/ac/index.php

I see LED taking more of a role in supplemental lighting in combination with halides or some other type of HID lighting of the future.