Reef Tank Energy Savings

[becks]

Also one has to account for the cost of t5 replacement bulbs

 

[DBR_Reef]

Also one has to account for the cost of t5 replacement bulbs

Bulb costs suck, I have to buy 12 every year, and I don't want to be the T5 defender, as I don't like running them by themselves (I also probably would not run LED by itself). BUT... if you had a 120g tank, and bought 2 xr30w for it that would cost 1300. A 48'' ATI sunpower is 650, and 5 years of bulbs is about 600. I would say at this point that a 5 year old LED is ready to be replaced (assuming that LEDs continue to progress at their current rate, for refference that would be a radion gen 1 right now), whereas a 5 year old ATI probably has another 5 years. And realistically coverage would be better with the T5 (I would probably want at least 3 radions if left un-supplemented), although I think the Radions might give better looking light. So I don't think LEDs are a more economical choice.

 

[mcarroll]

Leds have a higher theoretical efficiency, but I don't think that that has necessarily translated into real world savings- yet.

So there are a few things they have.....absolute efficiency of the emitter itself is one of them in most cases. But...

System Costs
I dunno if you've seen the numbers worked out on the system vs system costs over time, but LED wins hands down.

Power efficiency is only part of the action too....and I agree that depending on the ballast and bulbs in question, T5 or halide "can be" super efficient....but won't match LED. They're not trying, so let's not pretend too hard that this is a contest.

Because it's never that simple.

Power Costs
Folks that live where winter happens are unlikely to see a lot of money savings on the power bill....certainly not 1:1 with the power reduced from the lighting equation. Heaters will eat up some or all of the difference. I believe you would need to do some good work with a Kill-A-Watt meter to really know how much you end up saving in power.

Folks that live where they need to chill their tank, on the other hand, will benefit mightily by having their chiller run less.

Wavelength Costs
LED's do have a distinct edge in that they do not emit IR or other "waste" wavelengths that mostly just generate heat.

LED's, being a directed light source, also have the advantage in our application of generally "wasting" less light than most T5 or halide based systems. Mostly this is due to the infinitely superior control that LED's have due to the available lenses. The custom LED light on my 37 gallon is so tight that I almost never have to scrape algae from it....around once a year....but I still grow SPS under it from edge to edge.

All these things accrue to the efficiency of the LED.

Power Conversion Costs
I think percentage-wise lots of LED power supplies probably waste as much energy as lots of T5 and halide power supplies, so maybe that aspect of heating is more of a wash? Not sure on this...I'm betting it could depend heavily on the specific examples you compare.

 

[DBR_Reef]

System Costs
I dunno if you've seen the numbers worked out on the system vs system costs over time, but LED wins hands down.

Wavelength Costs

LED's, being a directed light source, also have the advantage in our application of generally "wasting" less light than most T5 or halide based systems. Mostly this is due to the infinitely superior control that LED's have due to the available lenses. The custom LED light on my 37 gallon is so tight that I almost never have to scrape algae from it....around once a year....but I still grow SPS under it from edge to edge.

I know LED's edge out T5 in efficiency (and this edge will probably increase), but I think it is closer that they are given credit for.

In terms of system costs minus energy- see above- I think it's pretty close unless you go with a DIY or Chinese black box. In fact I think T5 generally win here.

In terms of LED's being a directed light source, I agree- there is probably a lot of efficiency that come from this, and T5, being a distributed source probably wastes a lot. But that is also the point I was trying to make- that distributed light is an advantage in growing corals (at least I think so), and by removing that component and then claiming more efficiency does not compare apples to apples- you are removing a feature to gain that efficiency. LED's also often cover less of the tank- more efficient, but not really a good comparison if you want full coverage.

I'm not trying to bash LEDs- I'm running MH, T5, LED combo on my display- I just don't think LED's are the bargain they are made out to be.

 

[becks]

Bulb costs suck, I have to buy 12 every year, and I don't want to be the T5 defender, as I don't like running them by themselves (I also probably would not run LED by itself). BUT... if you had a 120g tank, and bought 2 xr30w for it that would cost 1300. A 48'' ATI sunpower is 650, and 5 years of bulbs is about 600. I would say at this point that a 5 year old LED is ready to be replaced (assuming that LEDs continue to progress at their current rate, for refference that would be a radion gen 1 right now), whereas a 5 year old ATI probably has another 5 years. And realistically coverage would be better with the T5 (I would probably want at least 3 radions if left un-supplemented), although I think the Radions might give better looking light. So I don't think LEDs are a more economical choice.

I was always under the impression that leds don't weaken with time, either the led burns out or it works, but the life span much depends on various environmental factors and how the unit is used by the individual. I have maxspect razors where I can just change the led pucks cheap enough.

 

[DBR_Reef]

I was always under the impression that leds don't weaken with time, either the led burns out or it works, but the life span much depends on various environmental factors and how the unit is used by the individual. I have maxspect razors where I can just change the led pucks cheap enough.

Leds definitely dim over time, their lifespan given is when they dim to 75% of their original output. But that takes far longer than 5 years- more like 10. But are you going to want 5 year old led tech on your tank- Because I don't think most people would. Obviously that "obsolete" lifespan will lengthen as development slows.

 

[TylerS]

As I was typing my post I was guessing my comment on LEDs would be the most "controversial". I agree there's arguments to be made for lighting sources other than LED, many of which have been brought up, but if we're just talking about efficiency LED is the way to go.

Here's a great post on this from page 2 of this thread:
https://www.reef2reef.com/threads/p...fit-1-the-perfect-light-balance.274031/page-2

Hi Ksed,

Thanks for this interesting question.
I hereby want to explain why we claim an energy benefit of at least 30% versus a T5 lamp based solution.

My apologies upfront. I have to go into technical details and have to use some lighting jargon to explain this clearly!
The short statement: The color point or even more correct, the spectrum of a light source, is of great importance for defining and comparing the efficiency of a light source (or technology).

Before I start the explanation I want to introduce two terms:

Optical Power
The term optical power (or radiant power) describes the energetic content of the light and is measured in Watts. This term has no additional weighing factor like Lumen/lux (corrected for the human eye sensitivity curve) or PAR (corrected for a range between 400-700nm).

Wall-Plug-Efficiency
WPE (Wall-Plug-efficiency) is the ratio between the amount of electrical input power and the amount of optical output power which the source produces.

A T5 tube (low pressure discharge tube) produces UV light with a wavelength of 254nm.
With the help of phosphorous coatings, these wavelengths are translated to longer wavelengths (that are more visible to the human eye, but also more useful for corals).
This transformation in wavelength introduces losses that depend on the gap between the base pump wavelength (254nm) and the desired wavelength (let’s consider in this example 450nm).

The typical efficiency of the T5 tube (converting electrical input power to optical output power of 254nm) is in the order of 70%. But these wavelengths should be transformed to the desired wavelength (450nm). This process introduces losses what is called “stokes shift losses”. If we consider a narrow desired wavelength of 450 nm (theoretical example) we can determine the stokes shift losses which are in the order of 44%!

For this example, the total theoretical maximum WPE of a T5 bulb is 70%*56% = 39.2%

If we look to the LED technology we actually perceive a similar trend.
One of the biggest differences between the Led ant T5 technology is the wavelength of the base pump.
For LED technology, the most efficient base pump is achieved around 450nm (instead of 254nm for a T5 tube).

If we consider the Luxeon T Royal Blue LED (that is also used in the CoralCare application) we can see that the WPE of this LED is in the order of 53% (under ideal conditions it produces 1040mW optical power at an input power of 1.96Watt). Because the base pump is already equal to our target wavelength we have no stokes shift losses and the final WPE of the LED is 53% for a wavelength of 450nm.

LED solutions suffer from the similar stokes shift losses, but because the base pump of a led source is much closer to visible and more useful wavelengths, the overall LED technology is more efficient (this is one of the reasons, but most of influence for this story!).

Now we apply this theory to a more practical situation:

The CoralCare fixture consists out of 5 LED types.

Luxeon UV 420nm
Luxeon T 450nm
Luxeon Rebel Cyan (~480nm)
Luxeon Tx 6500k white (a phosphor converted solution with an average color point is 6500k)
Luxeon Rebel Phosphor converter amber

Based on the presented theory we can conclude that if we would only enable the 450nm LED’s, the CoralCare fixture would be much more efficient (= higher WPE) than if we would enable other channels (which have stokes shift losses or lower WPE values).
This already explains why the color point, and even more accurate, the comparable spectral content is of great influence when comparing two lighting technologies.

Based on practical data:
If we would only enable the Blue channel (combination between 420 and 450nm) we would (including ALL optical, electrical, and other parasitic losses) achieve a WPE of 35.9% for the CoralCare solution.
If we would only enable the white channel (combination between Cyan, 6500K and Phosphor converter Amber) we would achieve a WPE of 28.3%.

Curious how we measure this?

The WPE measurements are performed in a special optical measurement sphere.
The light source is placed in this optical sphere and a light sensitive sensor collects all light radiation that is being produced by the light source (integrating sphere).
By also measuring the electrical input power, you can exactly measure how much electrical input power is transformed to optical power.

Here is a picture of the T5 reference fixture measurement
This sphere is one of the biggest optical measurement spheres in the world and has a diameter of 4meters! An extremely impressive measurement device.

So slowly building towards a conclusion.

We just showed that the theoretical efficiency increase between a LED and T5 source (with a specific wavelength of 450nm) would be in the order of 60% more efficient. This statement is highly theoretical and does not claim anything about practical applications.

But the principles of this theory are correct and need to be applied on an apple-to-apple source comparison. Therefor we chose to compare the two lighting solutions based on their WPE that were measured with help of the integrating optical sphere.

We took a reference T5 fixture with 6 AquaBlue special 12.000K bulbs as a reference and set the CoralCare fixture in a way it would match the color point of this bulb as good as possible.

The resulting spectral content is not 100% comparable (because the T5 consists of narrow peaks and the led solution has a more continuous spectrum), but it is as close as possible (assuming all practical limitations).

This results in a WPE difference of ~30%

This is done with brand new T5 bulbs (performed a burn in test as described in the measurement standardization norm) under ideal operation conditions.

This statement could be countered by stating: this is not a practical situation, most users use an even bluer spectrum by combining the Special Blue bulb with (i.e.) a blue or Coral plus bulb! This results in even higher efficiency differences for LED based solutions. The color point (and spectral content) is shifted more toward the shorter wavelengths of light (considering only wavelengths above the 400nm UV threshold) and therefor increasing the WPE even more for the LED solution.

Another note: bluer T5 bulbs degrade much faster in light output compared to warmer color tones.
This has to do with the degradation of the Blue phosphors that are affected by the highly energetic light from the mercury discharge source.

So in summary, we state that the CoralCare light brings an efficiency benefit of at least 30%.

In a practical situation this is even increased to over 50% within a few months due to the degradation of T5 bulbs.

PS. Some small correction from BRS’s measurements.
BRS accidentally included the losses from the 230V-110V converter in the power measurement.
The actual CoralCare fixture power is 187-190Watt (depending on ambient and core temperature of the fixture).

Please share your opinion and feel free to ask any questions!

 

[DBR_Reef]

As I was typing my post I was guessing my comment on LEDs would be the most "controversial". I agree there's arguments to be made for lighting sources other than LED, many of which have been brought up, but if we're just talking about efficiency LED is the way to go.

Here's a great post on this from page 2 of this thread:
https://www.reef2reef.com/threads/p...fit-1-the-perfect-light-balance.274031/page-2

Very cool testing! But now I want to know why we don't see higher par values from the coral care, considering their watts are about the same as the t5. Seems like we should be seeing on the order of 30% more par?

 

[TylerS]

The post I referenced covers this. Phillips team is not measuring PAR, and they're using much more sophisticated equipment (one of the best light measurement devices in the world?)

"Optical Power
The term optical power (or radiant power) describes the energetic content of the light and is measured in Watts. This term has no additional weighing factor like Lumen/lux (corrected for the human eye sensitivity curve) or PAR (corrected for a range between 400-700nm).

Wall-Plug-Efficiency
WPE (Wall-Plug-efficiency) is the ratio between the amount of electrical input power and the amount of optical output power which the source produces."

Maybe @Luc Vogels could chime in with a few more specifics on why PAR measured by a LI-COR does not show a difference between T5 and LED on that BRS video, but their measurement in a light sphere shows a 30% difference?

Regardless; I'm satisfied by the theory, detailed technical knowledge of phillips team and their LED competitors, and numerous practical examples of successful reef tanks running LED that they are more efficient.

 

[Luc Vogels]

Great Discussion!

It is very difficult to perform a correct apple-to-apple comparison between two different lighting technologies.
With different beam angles, spectra, and average colourpoint it is a challenge to really state which of the technologies is more efficient and why!

By standardising certain lighting aspects (what are defined by Consortiums in which all bigger lighting manufacturer participate) these comparisons are made more accurate for general lighting applications.
But even then, a comparison can be weighted differently of what the author thinks is most important (in example; a reefer can think that lumen output is less important than the achievable coral growth!).

So, skipping back to which technology is more efficient?
Well the short answer is, yes LED lighting is more efficient compared to T5 lighting.

Just as an example (don’t mind the numbers, they are estimates):

If we assume a general lighting application
Color temperature 3000Kelvin, CRI >= 90
A modern typical 3000K LED has an efficiency of about 140lm/Watt, a T5 lamp about 120Lm/Watt.
If we would perform an integrating sphere measurement (what counts ALL lighting photons that exit from the source) we would found numbers that are closer to each other.
This is perceived because the T5 lamp also generates some radiation at wavelengths (<400 and >700nm) that do not participate in the (to our eyes) visible light domain.
We weighted these values with an eye sensitivity correction curve that results in the “lumen” parameter.

But what happens if we implement these light sources in the physical application?
T5 is an omni-directional source and requires reflectors to point the light towards the application.
Such reflectors introduce light losses, and the system efficiency drops.
But also for LED lighting some penalties could be considered. Ambient (and LED junction) temperature of the LED’s drastically impact the efficiency of the device.

In present times, 80% of the conventional lighting applications are replaced by higher efficient LED based solution that outperforms the older technology.
But there are still some application in which conventional lighting still rules (think about UV-C lamps or high lumen density sources).

Now skipping back to our hobby … Light and reefkeeping.
The T5 source is a trusted and proven technology that works great to successfully grow a coral reef.
LED is also here “the new kid on the block” and should still prove itself to the majority of the experienced reefers.
Here we again try to compare two lighting technologies but introduce various weighting factors (i.e. coral coloration, coral growth, PAR) that complexifies this comparison.

For instance. I often read that users compare the PAR value they measure in their tank with PAR values of others users.
This without considering the differences in light parameters that drastically affect this value.
PAR is nothing more than the integral of all light radiation between 400-700nm of light.
So if I would design a lamp with 500nm LED’s and 700nm LED’s and achieve an equal PAR value, what do you think what happens when we introduce this light to our corals?
Well they are certainly not happy: http://images.philips.com/is/conten...7_001-UPD-en_GB-Photophysiology-of-corals.pdf

But looking from another angle.
Also, average color point or spectral content leads to different efficiency advantages.
As example, an LED (similarly as a T5 bulb) is more efficient (WPE) when it generates a cold (or blue) color tone compared to a warmer color tone.
This has to do with phosphor conversion (stokes shift) effects. So it is actually vital to make sure light sources or spectra CAN be compared to each other correctly.
Ultimately, weighted parameters as PAR can be used to compare lighting solution, but certain key aspects as spectrum and color point should be kept as equal as possible.

Coming back (with some detours) to the original question.
Why do we perceive a difference in results between the test in the BRS video, and the test we published on our webpage?
First of all; I think BRS made a great video and I am impressed how many knowledge they have, but there are two points (differences) that impacted the results (and comparison)

1. (already stated) the 230V to 120Vac converter was added to the power consumption (what is normally not the case when you drive it from the correct mains). The power consumption is ~190Watt
2. The color point of the two lighting systems did not match. The T5 solution had a more bluish color tone (benefitting more from increased spectral light generation efficiency of bluish color tones).

If both differences were removed, the results would be similarly compared to the once we published.

Hopefully this post contributed a bit to this discussion and clarified your questions.

Also please keep in mind that T5 bulbs degrade faster than most people expect.
Especially blueish wavelengths (what our corals are able to use most efficient) degrade the fastest.
An drop of 30% (of these wavelengths) can already be expected within 6-9 months.
For LED’s (when correctly driven and with sufficiently cooled) this point is reached after 25-50k hours.

Please let me know when you have additional questions about it!

The post I referenced covers this. Phillips team is not measuring PAR, and they're using much more sophisticated equipment (one of the best light measurement devices in the world?)

"Optical Power
The term optical power (or radiant power) describes the energetic content of the light and is measured in Watts. This term has no additional weighing factor like Lumen/lux (corrected for the human eye sensitivity curve) or PAR (corrected for a range between 400-700nm).

Wall-Plug-Efficiency
WPE (Wall-Plug-efficiency) is the ratio between the amount of electrical input power and the amount of optical output power which the source produces."

Maybe @Luc Vogels could chime in with a few more specifics on why PAR measured by a LI-COR does not show a difference between T5 and LED on that BRS video, but their measurement in a light sphere shows a 30% difference?

Regardless; I'm satisfied by the theory, detailed technical knowledge of phillips team and their LED competitors, and numerous practical examples of successful reef tanks running LED that they are more efficient.

 

[mcarroll]

But are you going to want 5 year old led tech on your tank- Because I don't think most people would.

You can't spend too much time worrying about what most people would do!

My LEDs are about 5 years old and still going pretty strong.

There's certainly nothing wrong with "old tech" as long as it worked to grow corals in the first place.

 

[bwmalloy]

Folks that live where they need to chill their tank, on the other hand, will benefit mightily by having their chiller run less.

Too true!!! @mcarroll has spent considerable time advising me on my rebuild and I couldn't be happier with the outcome from both standpoints of cost and performance.