Further Revised 10/8/15
- Emitter History & Construction
- Measuring Output Energy
- Simple How Do Plants Grow?
- Input vs. Output
- Useful Light Energy
- Blue Light Energy
- Plant Useful Energy
- Coral Useful Energy
- Effects on Output Energy
- Measuring Output Light
- Water Penetration
- Low-High Requirements
- Specimen Placement
- Emitter Combinations
- Watt per Gallon?
- Circuitry- Driver/Converter
- Current Reduction 0-10V vs. Pulse Width Modulation
From brand patents/exclusive license agreements, drivers, dimming, input/output energy, and more, the science speaks for itself!! The repeated experiences back up the science! Lighting and aquariums ARE science, albeit with art and personal preferences mixed in!
Picture above is of an office with many reef aquariums (which includes stony corals, SPS and LPS) set up with low input energy/high output TMC AquaRay LED systems, please click to enlarge
I try and mix simplified science for easy reading along with a lot of practical experience in this article. I cite many other related articles to back up the science and hopeful to make it easier for a overall easy learn of a very complex topic of aquatics. This information is backed up by experienced individuals, which I know well.
Very limited research in the area of lighting is being done in regards to aquarium applications. Much of this work is referring to other outside references.
If we can understand the overall aquarium LED fixture, we can make an informed decision on our aquarium LED purchases. This review also goes into interesting aspects of lighting, not needed to know for figuring out what LEDs are best for the application they will be used for. It is nice to know more usefulness of a light source. If we can learn how much is needed, learn what is only required and not wasted extra.
Please read ALL my cited references and consider reading my other articles about Aquarium Lighting. They provides some foundation to the hows and whys of this article.
Also note that with the latest revisions to this article, I have added more advanced lighting science information, this information is meant to back up the more basic information that this article was intended to get across. A full reading should provide the reader a very good understanding of what makes a good LED aquarium light for your planted or reef aquarium, but even skipping over the more technical sections should still help any reader make a more educated decision.
Here is one cited reference/source:
Aquarium Lighting; Facts & Information
For aquarium use, the development of LEDs (2007) for both reef and freshwater planted, was trying to get a high amount of energy (carried by Photons) into wave lengths of light used in aquarium photosynthesis (PAR). While this was important, ultimately delivery more output energy has been the big advancement for this new technically. Ultimately getting the most amount of energy in necessary frequencies for photosynthetic life with the least amount of energy used. This makes-up the total useable amount of energy. [PUR = Photosynthetically Usable Radiation] for whatever photosynthetic organism being grown.
While nothing about photosynthesis is required to be known in order to grow plants or corals, it’s nice to be able to read some of the specifics published by light manufactures. It does help us understand how effectively we are growing and does give an idea of the type of color and energy we can expect from our light source.
For the whole LED fixture as a whole, essentially, the best LED fixtures are NOT aquarium lights in the traditional sense, even the emitters are not a “bulb” as many people think. They are a computer chips making micro-explosions, emitting frequencies of waves. Some of these waves, we know as light.
High end LED fixtures use complex circuitry to precisely spread electoral voltage over drivers, which control each emitter. LEDs properly driven will give large amounts of precise frequencies and not shift or loss energy (spectrum), unlike ALL fluorescent lights.
For other LED fixtures, this statement cannot be made, because emitters are not properly driven (ie. Christmas lights, no driver/converters), daisy chained together, in a shotgun approach to output energy.
For those who are unsure as to what a quality low input/high output LED can do for their reef aquarium or think these are still untested even as of 2015, here’s an excellent newer website documenting the marine LED research at Saint Mary’s College of Maryland by Dr. Walter Hatch, showing better growth, spawning, and more.
St Mary’s Marine Biology Experiments with LED Lighting
Sustainable Reef- Optimal Growth at Low Energy Consumption
At the end of this review, we should be able to understand these light measures of LED, which few are used for useful light produced by the source. We will start with the most useful by today’s science and work backwards.
The three reviewed will be PAR as most important, Spectrum, then Corrected Color Temp Kelvin. There are other measures used, but are less useful for understanding how much LED is needed.
This review also goes into aquatic light measurement meters and how they read output energy.
Based on research and interviews, beginning in 2007 [and continuing to improve as of 2015], high end LED aquarium lighting started to become a viable replacement for metal halide in reef tanks under 30 inches and surpass most T5 aquarium lighting as soft and hard corals are able to thrive under the newer exacting high output LED’s.
This is not only due to the exact energy (light) output, but more due to the amount (quantity delivery output) of frequency LEDs are able to provide for low input energy used. LEDs have both quality and quantity light for specific applications we want to use them for.
By this time, many planted freshwater applications were already having success with LEDs, such as the 6500K [high energy white] PAR 38 lamps.
This needs to not be confused with the low output 3000K PAR 30 sold at Home Depot as an example.
6500K PAR 38 Planted Aquarium Lights
Emitters are driven at different intensities to provide more momentum (speed) of higher intensities of output energy (some visual to the eye) by utilizing certain compounds. This process converts input energy into focus carrying particles (Photon), which in them self carry different intensities of frequencies (output energy) known as light delivered to plants and corals.
How emitter diodes are created can be complex and precision equipment has to be used to compile the light diode. A substrate material is used and layered with other materials, which takes input energy and delivers output energy through a lens.
Brief overview of LEDs:
How LEDs Work
A graph later in this article shows blue light being most efficient, followed by red, then blue. The green is 50% less efficient than the red, and a whopping 80% less efficient than the blue. [Explained more below, please click HERE].
Further Reference, including a further explanation of the LED vs MH Plant experiment pictured above:
Real World Application of RQE, PAR. PUR, PAS, & Photons
Having high amounts of frequencies dialed in [quantity first followed by quality] is what’s important.
One way to think of the high end LED fixtures, not other LEDs such as a LED flashlight… these are computers, which emit frequency wavelength needed for tank inhabitants.
[See Proper LED Ventilation].
They’re name brand emitters, which are known by many people, because their name is backed up. Phillips, Cree, Osram, Bridgelux are the most common names. It’s typical for larger name companies to have more funding behind their lighting research as well.
Cheaper fixtures will use no name emitters.
Different emitters can have the same appearance rating, but not have the same quality and quantity of output energy to create the overall visual/non visual spectrum [PUR]. 6500K from Cree is not going be the same makeup/output or visual as the same as a 6500K from Phillips or Bridgelux. There will be differences in the way they are driven for more or less momentum giving less or more force for delivery. There’s differences in straight 6500K (White) emitters and differences in the overall combination of emitters/color to make an overall specific output energy and visual color rating [Kelvin Section].
This comes down to cost/budget-supply/demand [marketing & research], of how fixtures are put together. No named emitters are a flag for how quality a fixture will be and what you should expect to pay for it. Different emitter companies will have standards [some patented/specific application agreements or licensing] of how they design their frequencies and will also have different color selections.
These differences will create different quantity [PAR]/quality [PUR] for aquatic photosynthesis [plants, corals, algae].
Input vs. Output Energy
It comes back to these terms/graphs, where all have an important role in how they work individually and how together synergistically to make up important overall PAR as well as PUR for the application of aquatic plants and reef coral.
Photosynthetically Active Radiation– (PAR) designates the spectral range (wave band) of solar radiation from 400 to 700 nanometers that photosynthetic organisms are able to use in the process of photosynthesis. This spectral region corresponds more or less with the range of light visible to the human eye. New science is exploring more out of this range.
Aquarium Lighting; PAR
Wiki- Photosynthetically Active Radiation
RQE– All energies used by a plant in the full photosynthesis process (when all energies are provided from a full spectrum, such as the Sun) (RQE Mcree 1972) RQE is how a PAR meter measures.
Blue Light– The largest energy out delivery of frequency energy delivered by Photons for the photosynthetic process [more intense delivery better for penetration of water and cellular body structure as well.
Energy used by Zooxanthellae’s in the full photosynthesis process.
Full Spectrum of the Sun.
Frequency of energies carried by Photons
Amounts of Red, Blue, and Green (all colors from the Visual Spectrum, RBG are primary colors) mixed together create a White appearance to our eye [Kelvin/CRI], just like if you were to mix all plaint colors and get black. These colors mixed can make a quality of energy.
Colors are combined for a visual appeal, but they are also combined in different efficiencies to create a White, which is the most useful (energy wise & considering visual too). This aspect of light is highly researched, with about 1 billion dollars going to the research (as of 2015).
Using more intense deliveries of energy by them self (Blue & Red) have also been proven to be useful for when an limited amount of energy is used but a higher output is needed. Research has shown there are pros and cons (growth and visually), when using these colors exclusively.
Simple How Do Plants Grow?
Imagine plant photosynthesis as a battery and once the battery is full, the plant can produce an action, which growths the plant. Certain energy can fill this battery quicker, other takes long, but still fills the battery. These energies are studied and can be seen in the RBG LED study above and RQE.
[More to come]
This section will accompany the video to quickly understand how we get more energy out of a fixture.
Measuring Output Light
Once the energy is delivered out of the fixture, here are the matrixes we use to measure the light.
Photosynthetic Active Radiation (PAR) Quantum Meters:
“Photosynthetic Photon Flux (PPF)” – Common to the hobby.
“Yield Photon Flux (YPF)” – Industrial (more weighted measure)
This is a measurement of energy contained in a particle.
The best matrix for measuring useable light energy is Photosynthetic Active Radiation (PAR).
We have two understandings of PAR and one can be considered more useful.
The best way to describe these measurements is to let the experts do the explaining:
Photosynthetic Photon Flux (PPF)- (µE m-2 s-1 above)
“The most common method of measuring PAR gives equal value (amount of energy carried in photon) to all photons with wavelengths between 400 and 700 nm and is referred to as the photosynthetic photon flux (PPF)…”.
However, photosynthesis is driven by photons with wavelengths below 400 nm and above 700 nm, and photons of different wavelengths induce unequal amounts of photosynthesis… [seen in Mcree RQE]
*Graph showing both PPF and YPF PAR readings
Yield Photon Flux (YPF)-
“Photosynthesis is fundamentally driven by photon flux rather than energy flux, but not all absorbed photons yield equal amounts of photosynthesis. Thus, two measures of PAR have emerged: photosynthetic photon flux (PPF), which values all photons from 400 to 700 nm equally (ideal), and yield photon flux (YPF), which weights photons in the range from 360 to 760 nm according to plant photosynthetic response…” (average plant response).
“For these reasons, an accurate measurement of PAR should follow the relative quantum efficiency (RQE) curve originally developed by McCree (1972), which weights the photosynthetic value of all photons with wavelengths from 360 to 760 nm. A sensor that responds according to this curve measures yield photon flux (YPF)…”
“The Stark-Einstein Law states that one absorbed photon excites one electron regardless of the photon’s energy between 400 and 700 nm; this law is the basis for weighting photons equally. However, although >90% of blue photons are absorbed, 20% of these photons are absorbed by inactive pigments; their energy is not transferred to energy-collecting pigments (reaction centers) and is lost as heat and fluorescence. This loss means that the quantum yield of absorbed blue photons is typically 20% less than the quantum yield of absorbed red photons. Species differ in their proportion of inactive pigments…”
“genetic and environmental influences on quantum yield…”
“In spite of these genetic and environmental influences on quantum yield, McCree (1972) found that the spectral quantum yield of healthy, green leaves of 22 crop plant species differed by less than ±5%, so he defined an average RQE curve. Inada (1976) obtained a second set of comprehensive quantum yield data (from 33 species) and confirmed McCree’s (1972a) measurements.”
“Quantum sensors designed to measure YPF or PPF are commercially available. Both types use multiple-spectral filters in front of a broad-spectrum radiation detector…but neither type matches its desired curve ”
Accuracy of Quantum Sensors Measuring Yield Photon Flux and Photosynthetic Photon Flux
PAR Quantum Meters available to most hobbyist and measure Photosynthetic Photon Flux (PPF), which values all photons equally, which is the first mismeasure of weighted photons in the range from 400 to 700 nm. According to plant photosynthetic response, Yield Photon Flux (YPF)is the best measure we have.
This is a measurement of energy as wave frequencies.
At this point, we can assume this is the energy make-up in each photon delivered. You could image each photon carrying this spectrum.
Remember there can be a make up one just one of the same emitter or many different emitters. So we would have to image different spectrums for each photon depending on the spectrum of each emitter. Added all together.
Quick how we measure energy frequency radiation.
The electromagnetic spectrum is the range of all possible frequencies of electromagnetic radiation. The “electromagnetic spectrum” of an object has a different meaning, and is instead the characteristic distribution of electromagnetic radiation emitted or absorbed by that particular object.
Electromagnetic Spectrum- Wiki
For an easy example: Spectrum of a 6500K AquaRay GroBeam, using ALL Cree 6500K XB-D emitters
All spectrums found on a fixture box will be a rough estimate of the overall spectral make-up of all combined emitters averaged. Some fixtures use all the same emitter. This spectrum is the energy emitted from the one emitter.
MORE useful information would be to understand each emitter in the fixture If considering each emitter, wattage of each emitter can be considered for total output of the fixture.
[Input vs Output]
-The example above is of a 6500K white [Kelvin below] aquarium plant emitter.
Consider the spectrum of the Sun, shown earlier in the review
***See how their different and what could be considered as useful. We know all energy is useable, so we want to provide it to our plants.
Allowing the plant to chose what it wants to use, when it wants. Different energy is used for different process such as growth or vegetable production [We can focus on these spectrums if we know what the plant needs at a given time/season]
With a limit input energy, we have to consider our maximum useful output, by using what we know about energy delivery [blue is most efficient]. It will charge the plants “battery” the fastest.
So what do we do with limit energy inputs, we focus more input energy in delivery of photons with the most more efficient spectrum. This is really what has allowed us to take huge steps in aquatic technology to get the most efficient lighting (T12-T2- now to LED). WHILE trying to provide all energy, which plants find useful in someway.
So, we add our higher energy out blue. Photon delivery of more energetic energy [frequencies].
AND, we try to get our FULL BODY spectrum, similar to what we know the Sun provides.
Now, this can be done in a million different ways, including, just using one narrow energy spectrum emitter (one color) only, OR using a White emitter combined energy (Photons carrying frequencies, with unequal responses on photosynthesis), OR using separate energy (color) spectrums and adding them all together to get the overall output frequency energy.
Different emitters will have more energy focused in different spectrums, either blue frequencies, more maybe in the middle of PAR (Green-Yellow) frequencies.
By taking a look at the spectrum of each emitter, we can get a estimate of how much input energy is going to different output spectrums desired.
Why not just provide the same spectrum as the Sun?
When considering a limit energy supply like an artificial light, we cannot just provide the same spectrum as the Sun, as we would actually get less efficient growth, considering what we know about photosynthesis and frequencies. By using what we know (ultimately adding more blue or red spectrum to our output), we are able to use less input energy and get more useful output energy. If we used the Sun spectrum as the only frequencies we provide (all frequencies), we would get growth and the plant would be healthy, growth would just be limited to the input energy supplied.
If we didn’t have to worry about input energy, providing more energy in all frequencies would be best (Sun), allowing whatever photosynthetic creature to use whatever it wanted, whenever it wanted.
So, in a general sense, having high amount of blue energy and a full body spectrum is best overall usefulness, cause it give us the intensity of the blue and the full body, which is needed for the plant or coral to use. Whatever it needs. When it needs it… [different plants need different frequencies in different conditions and environments.]
We could also imagine this spectrum being carried in every photon:
Typical PAR action spectrum, shown beside absorption spectra for chlorophyll-A, chlorophyll-B, and carotenoids
–Photosynthetic Action Spectrum– (PAS) An action spectrum is the rate of a physiological activity plotted against wavelength of light, It shows which wavelength of light is most effectively used in a specific chemical reaction (Plant & Zooxanthellae photosynthesis).
Some reactants are able to use specific wavelengths of light more effectively to complete their reactions. For example, chlorophyll is much more efficient at using the red and blue spectrums of light to carry out photosynthesis. Therefore, the action spectrum graph would show spikes above the wavelengths representing the colors red and blue.
This spectrum has been shown to be very efficient for growing a plant and the large process chlorophyll plays in photosynthesis. This is one option to focus our spectrum as well, but we have to consider the rest of the spectrum as well and visual appeal for an aquarium.
Lights will have Kelvin rating, which is a unit of measure for temperature and is commonly used to describe the type of light one can expect to see from a light fixture and is loosely connected to the light energy in Nanometers.
Simply put Kelvin Temperature is basically a measure of color hue and different hues “colors” have been shown to grow more plant mass or fruit production…etc. Generically speaking though, Kelvin is not an accurate prediction of the photon frequency/ nanometer wave length.
Kelvin is the color a black body radiator (such as the Sun) is when it heats up. The sun highest in the sky, plus blue sky equal 6500 Kelvin. The Sun lower in the sky and later in the seasons, will be warmer at say 3000K. These seasons will have different growing effects on photosynthesis.
Stars which are hotter or even fire, will have a blue appearance, which we might rate at a 12,000K blue Kelvin.
The color temperature (what we see) of a light source is the temperature (Kelvin) of an ideal black-body radiator, which radiates light of comparable hue to that of the light source. Color temperature is a characteristic of visible light.
The CIE 1931 x,y chromaticity space, also showing the chromaticities of black-body light sources of various temperatures (Planckian locus), and lines of constant correlated color temperature.
Color Temperature- Wiki
In physics and color science, the Planckian locus or black body locus is the path or locus that the color of an incandescent black body would take in a particular chromaticity space as the blackbody temperature changes. It goes from deep red at low temperatures through orange, yellowish white, white, and finally bluish white at very high temperatures.
Planckian Locus- Wiki
These colors will go from white to cooler blue or warmer yellow/red.
This measure was at one time the way we measured energy, when the relationship between heat emitted and energy was being studied. Today’s studies looks at energy in particles [photons] being the ejected light source emitted and not frequency waves emitted by heat.
Another popular trend is LEDs allowing the user to control color temperatures. These RGB and capacitive touch features are more for personal experience, which are popular for more personal visual appeal and coloration.
Other RGB features utilize green, red, yellow, and other color emitters.
As far as low input/high out or overall construction there’s little benefit for the RGB feature and in fact, they sometimes can be stressful/harmful to all aquatics and can encourage algae growth in certain situations.
As a generalization, the use of more blue and/or higher Kelvin daylight (more output/more delivery) is necessary for specimens, which are deeper in the water column (such as 14000K daylight for depths past 12 inches). Another consideration is whether the emitter is wide angle or more focused, as this can determine which emitter combination is best based on specimen placement.
For instance a Maxima Clam, which is placed on the bottom of a 24 inch deep tank will likely do best with more intense focused Reef Blue emitters (50,000K @ 465-485nm) in the emitter mix, or even supplemental 20,000K Metal Halide.
Or better, I would be placing the Maxima Clams on shelves higher up on your “live rock” reef. (provide better lighting to your clams, and keep the clam off the bottom away from bristle worms) Depending upon how far under the surface you place these and other photosynthetically sensitive inhabitants will allow for more wide angle LEDs for better overall spread and more energy to get to the specimen.
Coral such as an Acropora placed the reef at 6 inches under the surface may do well with lower daylight emitters, Which still have a some energy output and light spread.
Acropora could also thrive on the bottom of the tank, with enough output energy, a focused force with more momentum.
With freshwater plants, this also holds true to some degree, so if a tank is well terraced, standard 6500 daylight emitters should be fine for most plants up to 20 inches, however adding higher Kelvin daylight, such as the Marine White 10-14000K might be suggested for tanks deeper than 24 inches.
Fixtures can be made of one energy output or a combination of a few to many. Few emitters can be used, more, to many. The way they are made up and driven are how we come to an overall PUR.
A major determining factor for which output emitters used (in color/PAR output) is in fact getting more energy down to whatever is being grown. For example all the high light requiring specimens placed 30 inch deep tank, I would know I need more energy output for delivery, so I would consider blue in my spectrum.
Best is to use least amount of the spectrum spectrum desired and not averaging the total energy over many different spectrums.
Also where a certain emitter is placed and it’s spread, will have an effect of group, really under the spread of the emitter, not over the entire spread of the tank. Photosynthesis depending on plant, could be different from under a blue emitter to under a warm white emitter. While the overall spectrum is rated for the fixture, that spectrum is not going through the whole spread.
Different whites, say cool to warm whites will be different growths as well.
In other words the newest generation LED emitters such as the similar patented CREE emitters would only require about .6 watt per gallon for high light planted aquariums and .8 watt per gallon for most reef tanks (under 24 inches). About .2 watt per gallon can be added to either (FW or Reef) for even more light or more depth over 24 inches.
However this does not apply to the many lower end LEDs now flooding the market such as the “New Fluval LED Lights” which provide little specifications other than CRI, which is not a parameter that should be used to rate any aquarium lights. These would be more like 1.5-2 watts.
Citation: Aquarium Lighting; CRI
What is missed by many LEDs, is the drivers/circuitry used to power each emitter. Like daisy chaining Christmas lights together, one simply daisy chains an LED emitter without changing voltage to each emitter in the chain. It’s this circuitry, which separates 80% of LED fixtures from the 20%, which have the proper circuitry and thus are more expensive drivers to maintain exacting voltages between each emitter.
Emitters are meant to be ran at a certain voltage to maintain their spectral quality.
A fixture will first need drivers, which are able to dim. Some have drivers not for dimming.
By design there’s two ways to do this. One with a different method more managing the incoming current. O-10V dimming and PWM. 0-10v is a simple adjustable rheostat adjusting the voltage, which effects the current. PWM is a flashing the volts, without affecting the current.
With any DC electoral (vs. AC) source, without the proper dimming methods and dimmed, the emitters will have an increase of current applied to them, which will stress on the emitter. Over time, especially when moisture is involved, this stress can lead to degradation of the emitter and it will burn out. With even one emitter burnt out, this can cause shifting of the lighting spectrum. This is how it’s explained by a Electric Engineer.
The shift of a LED lighting spectrum can be seen by using an incandescent bulb as an example.
This applies to both LEDs intended for Reef and Planted aquariums and by theory, can be different depending on how many emitters are chained together. Say 10 versus 300.
This concept applies to controllers, which dim and brighten an LED (built in or Apex). A controller best maintains the voltage output via pulse width modulation [PWM]. This applies to fixtures, which do have a dimmable driver in the unit and allows it to use this controllers using PWM.
Only a few brands offer this technology and can also be incorporate in DIY set-ups easily and at a decent price ($8).
Fixtures with PWM drivers, cannot be dimmed with standard 0-10v dimmers, such as Apex.
PWM is important as it’s effectively turning the LEDs on and off very quickly (faster than the eye can see) so there’s no change to the voltage/current output as opposed to using 0-10v linear or analog reduction (aka current reduction)/manual intensity controls used by many brands of LEDs.
This technology also will lower the watts to be used in LED fixtures proportionate to the voltage used, which will in the end save in operation costs. 10V dimming will always used 10 volts, where PWM is proportionate, so dimming at 5 volts will use 5 volts of energy.
“The main advantage of PWM is that power loss in the switching devices is very low. When a switch is off there is practically no current, and when it is on, there is almost no voltage drop across the switch. Power loss, being the product of voltage and current, is thus in both cases close to zero. PWM also works well with digital controls, which, because of their on/off nature, can easily set the needed duty cycle.”
See also this video explaining PWM, which I can almost guarantee if your LED fixture uses a cooling fan is NOT USING PWM.
YouTube Video Circuit Skills: PWM [Pulse Width Modulation]
HOWEVER, this technology is not cheap! Up front. Compared to the lesser brands on the market, the cost might be $100-$200 more. But, the idea is to save more power for savings down the road. Also to preserve the life of the LEDs, which is also applied to savings of not having the replacement emitters/fixtures.
The vast majority of LED fixtures utilize 0-10v current reduction (manual controlled rheostat), which can alter the light spectrum and also produces much more excess heat due to how “current reduction” (Voltage/Current relationship) works.
As well, while some Chinese LEDs are now being supplied with PWM, these utilize a basic form similar to how an electronic DC to AC Inverter can use square wave, modified sine wave, or pure since wave; with pure sine wave being best and most efficient and square wave being poor and inefficient.
This is also another reason why so many high wattage output LED fixtures require a fan. As the heat created by the amount of emitters on the sink sink (including excessive heat from dimming) is more than the sink can handle. This includes both low end LEDs or even many of the “better” more popular brands.
What’s also worthy to note is this wasted heat then requires a cooling fan, which represents more wasted energy, which could have gone into lighting output your aquarium. Wasted energy converts to heat… This is why ANY aquarium LED utilizing “linear or analog reduction”, which is the vast majority, requires a higher wattage, often with more emitters to provide the same useful amount of light energy/PUR so as to provide the same results as an aquarium LED that utilizes PWM and drivers!!! Lesser fixtures can waste up to 50% of it’s energy used in a combination of extra parts (fans) requiring energy, wasted heat, and poor spectral quaility/quantity.
With Current Reduction, you are wasting considerably more energy not just in wasted heat, but also when lights are dimmed. If you dim your lights at night, you are still using considerably more watts of electricity than with PWM.
PWM uses only the amount of energy required to drive the emitters at the voltage required. This cannot be said for a simple intensity control (even little digital screens intensity controls)!
So the long term energy costs with any LED, which uses extra parts, poor circuitry/current reduction (MOST), is going to be considerably higher, often paying for the PWM tech. in most cases under a year!!
Sum it up:
While Current Reduction and PWM both have their own pros and cons, from the aspect of a quality LED fixture, the lack of PWM (& use of Current Reduction) along with daisy chaining of circuitry is just one MAJOR reason NOT to consider ANY LED, which uses dozens of emitters to provide the amount of desired light lumens.
In fact, even an emitter from a “newer” bin such as Cree XTE, which is simply daisy chained together, will lose emitter spectral quality too if they are just used in current reduction. Versus the same Cree emitter, which has the correct constant current drivers to tie each and every emitter together.
Fixtures will have anywhere between three months to 5 year warranties. Some are full replacements or repairs. Some require a certain % of the emitters to have failed. Also consider the Money Back Policy.
Lack of proper circuity can also cause much quicker degradation of the circuitry. The result is often a much shorter LED fixture lifespan (not the 50,000 hrs emitters are rated for), which is why so many, if not most LED makers only warranty their product for 3 years or often much less. Often less… (heat damage from fans plays a major roll in shortening of the life of an LED fixture).
This is where it’s rather disingenuous [in my opinion] to advertise a 5 year lifespan while only warranting a product for a year. Most times, the fan will even stop working well before the life span of the emitters, making the advertised lifespan useless.
For this reason a fixture should just be expected to be replaced after the warranty period is up. Many fixtures do last past this point, this is just a good starting point for consider replacement costs.