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

[sphelps]

Steve, the fact that you measured a 40% drop in par and 32% drop in LUX would suggest the two are directly related. The difference of 8% is minor considering the likely test conditions and equipment used . Anyways the point I was making as a shift in CCT (not PAR) does not necessarily mean your par has dropped, depending on the bulb and ballast it could mean an increase or a decrease in PAR meaning the two are not directly related. A decrease in PAR is simply a result of an overall decrease in intensity which could be measured in LUX. The argument was that LEDs last longer than halides because they don't suffer the CCT shift meaning a more stable PAR reading over time, I suggested this isn't the case.

Producing a standard LED replacement for fixtures is no different than any other lighting type, they've already adapted LEDs to fit into almost all standard residential applications. This is no different, first the standard is introduced and then manufacturers build fixtures to accommodate them.

Retro kits are different than fixtures but yes there are good looking and bad looking fixtures for almost everything. Currently the LED fixtures I've seen are more in the cheaper plastic look like cheaper halide and T5 fixtures, nothing really high end yet with the exception of a few module based fixtures such as the AI but the module design itself isn't visually appealing IMO. Realistically this is a very small constraint and can be easily overcome.

Most dimable or controllable lighting fixtures are based on a standard 0-10V system. While not everyone would require the ability to externally control their light fixture it should certainly be an option. One would think with the current patent on LED fixtures with built in controllers having a 0-10V plug in for an external controller would be a good thing.

Proper design of a heat sink could maximize the inductive heat transfer eliminating the need for fans. Fans are needed in the current fixtures because the heat sinks are simply standard units not designed specifically for LEDs and therefore requiring addition convective cooling. Designing the heat sink to concentrate additional surface area at the LED locations would be the first step. There are also different grades of aluminum or other materials which offer higher inductive properties than what is probably being used. Fans simply cut the cost of the heat sink dramatically which is why they are used. Eliminating the fans would actually increase quality and reliability since fans often fail or become restricted over time which could result on over heating. Also using fans will result in an uneven heat distribution meaning some LEDs will run warmer than others. These two problems could explain why fixtures have suffered from LED failure, I can't imagine any fan lasting for 10 years over a SW aquarium. Eliminating the need for fans would definitely increase reliability.

Perhaps the warranty isn't as big of an issue. Most other fixtures and equipment we use is usually limited at 1 year as well. The difference with these LED fixtures is they are new and marketed as something that will last 10 years and save you money in the long run. Manufacturers could back up these claims by offering better warranty and with a higher end fixture I would expect it to be that way but perhaps such a fixture doesn't exist yet. I wouldn't expect the warranty to cover every component but if I look at my RD pump it was marketed as an efficient quality pump designed to last longer and therefore actually save you money in the long run. It comes with a lifetime warranty on the bearings. I've had bearings fail on other pumps and while it's not the only component that can fail it still says the manufacturer is standing behind there claims and product.

[OceanicCorals-Eugene-]

Originally Posted by sphelps

Proper design of a heat sink could maximize the inductive heat transfer eliminating the need for fans. Fans are needed in the current fixtures because the heat sinks are simply standard units not designed specifically for LEDs and therefore requiring addition convective cooling. Designing the heat sink to concentrate additional surface area at the LED locations would be the first step. There are also different grades of aluminum or other materials which offer higher inductive properties than what is probably being used. Fans simply cut the cost of the heat sink dramatically which is why they are used. Eliminating the fans would actually increase quality and reliability since fans often fail or become restricted over time which could result on over heating. Also using fans will result in an uneven heat distribution meaning some LEDs will run warmer than others. These two problems could explain why fixtures have suffered from LED failure, I can't imagine any fan lasting for 10 years over a SW aquarium. Eliminating the need for fans would definitely increase reliability.

If you look closely at well designed heatsinks they all incorporate fans to dissipate the heat and thats because most components work better at lower temperatures. One of the things that you see heatsinks on mostly are computer parts, there are heatsinks that are "silent" and require no fan but run the processor at 10-20C higher than the same heatsink with fans. The design of the heatsink itself is definitely going to help with the heat dispersion but if these units are run without a fan you/we can all expect them to never meet the 50,000hr that the manufactures claim. The main reason is heat, the lower the heat you can keep on the LEDs the more efficient they run, and the slower the intensity drop on the LEDs as well. If you want to see an example, wire some 5mm leds and put them in isolated environments of room temp, 50C, 80C you will no doubt see the 80C intensity drop along with a major color shift as well.

If manufactures actually source out reliable fans for there fixtures, like those found into computer cases, low RPM high CFM fans the units will be near silent yet still provide the cooling needed for the LEDs. Some companies will still try to build fanless LED fixtures, elos is one that comes to mind, but they dont drive the LEDs to its full capacity in those fixtures. But again it all comes down to what the company wants to do with the units, so i think what needs to be understood is how to channel the air flow inside the fixture itself to provide efficient cooling so that all emitters get cooling thats somewhat the same.

[Ron99]

I think it is not only heatsink design but the overall fixture design as well. Convection cooling can work if the heatsink is open to the air and visible. if you want to enclose it in a housing then you need fans to help move air. And even if open to the air fans will help keep the LEDs cooler than convection cooling alone.

My fixture is enclosed in a housing and I am running 3 low RPM computer fans. I cannot hear the fans at all (well maybe if I put my ear right next to them) and my heatsink is very cool. So I expect very long life out of my array with no noise. The fans should last as they are low rpm thus putting low stress on the bearings and are on top of a closed housing. Unless the location of your aquarium is excessively humid or you frequently splash water up and over your light fixtures I don't see fan reliability being a huge problem.

If you look at the Solaris fixtures that suffered LED failures it was not likely due to the fans but to the fact that there were no real heatsinks to help draw heat away. The heatsink setup of the Solaris units was completely inadequate and I do not think it is representative of what should and could be done with LEDs.

[StirCrazy]

Originally Posted by sphelps

Steve, the fact that you measured a 40% drop in par and 32% drop in LUX would suggest the two are directly related. The difference of 8% is minor considering the likely test conditions and equipment used .

A decrease in PAR is simply a result of an overall decrease in intensity which could be measured in LUX. The argument was that LEDs last longer than halides because they don't suffer the CCT shift meaning a more stable PAR reading over time, I suggested this isn't the case.

wohwoh man, I never said they wern't related only not the only factor. the simmple fact is if the big blue spike shifts to the left, PAR will drip off as it shifts compound this with a decrease in intensity and it will be compounded.

you can not gage PAR out put with LUX, two totaly diferant and unrelated measurments. you are in one case measuring the amount of the emitted light with in a specific wave length, in the other you are measuring the amount of visiable light that falls on a given area. kind of a mass vs PSI but of different componants. Like I said in the previous post, no two MH or T5, ect age identicaly. this is due to various factors, including gas concentrations/types inside and so on. LED eliminates this by using a solid state chip encapsulated with no air/gas/ect surounding the chip, but they do have a problem as mentioned... heat. if they are allowed to warm up they will go through a reduction in PPF, which rises again once cooled. this can be as much as a 30% reduction in as little as 1/2 an hour with out any cooling and no drop in intensity. so using a heat sink and fans properly is a twofold benifit.. maintains the PPF output and the life on the LED. I think you would need the fans personaly, other wise the fixtures would be huge inorder to give each LED enough heatsink to make passive cooling possible. by having fans and preperly using them you will be able to produce lighter, more sleak fixtures. for what it is worth I had 4 computer fans running over my sump for 8 years starting and stopping 4 times a day. although they were coated with salt spray they still worked..

Steve

[StirCrazy]

Originally Posted by sphelps

Perhaps the warranty isn't as big of an issue. Most other fixtures and equipment we use is usually limited at 1 year as well. The difference with these LED fixtures is they are new and marketed as something that will last 10 years and save you money in the long run. Manufacturers could back up these claims by offering better warranty and with a higher end fixture I would expect it to be that way but perhaps such a fixture doesn't exist yet. I wouldn't expect the warranty to cover every component but if I look at my RD pump it was marketed as an efficient quality pump designed to last longer and therefore actually save you money in the long run. It comes with a lifetime warranty on the bearings. I've had bearings fail on other pumps and while it's not the only component that can fail it still says the manufacturer is standing behind there claims and product.

ya warenty is a tough one.. I can build you a light fixture that is bullit proof, but I can guarentee the ballasts or bulbs will last more that what the warentee I get when I buy them.. now pumps and berrings is a different story, there is no reason any manufacture can't offer life time warenty on berrings as you'll find that is any simular sized pump designed to do the same thing the berrings will be very simular if not the same. I have been rebuilding pumps as part of my former job for over 20 years and it was very very rare I came across a berring problem. most of the time the pump wore out befor the berring did. but we did change berrings on some just becaue they are very cheep and we were rebuilding the rest of the pump, but I did save the old berrings for emergency spares..

Steve

[sphelps]

Originally Posted by StirCrazy

wohwoh man, I never said they wern't related only not the only factor. the simmple fact is if the big blue spike shifts to the left, PAR will drip off as it shifts compound this with a decrease in intensity and it will be compounded.

you can not gage PAR out put with LUX, two totaly diferant and unrelated measurments. you are in one case measuring the amount of the emitted light with in a specific wave length, in the other you are measuring the amount of visiable light that falls on a given area. kind of a mass vs PSI but of different componants. Like I said in the previous post, no two MH or T5, ect age identicaly. this is due to various factors, including gas concentrations/types inside and so on. LED eliminates this by using a solid state chip encapsulated with no air/gas/ect surounding the chip, but they do have a problem as mentioned... heat. if they are allowed to warm up they will go through a reduction in PPF, which rises again once cooled. this can be as much as a 30% reduction in as little as 1/2 an hour with out any cooling and no drop in intensity. so using a heat sink and fans properly is a twofold benifit.. maintains the PPF output and the life on the LED. I think you would need the fans personaly, other wise the fixtures would be huge inorder to give each LED enough heatsink to make passive cooling possible. by having fans and preperly using them you will be able to produce lighter, more sleak fixtures. for what it is worth I had 4 computer fans running over my sump for 8 years starting and stopping 4 times a day. although they were coated with salt spray they still worked..

Steve

Agreed that you can't measure PAR from lux directly, obviously the PAR of a bulb depends on the spectrum distribution. However that was never my point. I'm purely talking about bulb wear and the simple fact is a decrease in PAR over time is the result in an overall decrease in intensity which could be measured by LUX. For example mass and psi are separate measurements but if you have a mass over a given area and the area and gravitation force remains constant then a decrease in PSI means a decrease in mass.

Your "big blue spike" does not shift, or move to the left or right, it simply decreases in intensity and the overall CCT shifts to a lower K rating. Depending on the bulb you can also see an increase in other areas of the spectrum like red and green which is why some bulbs will actually increase in PAR overtime or stay relatively constant. In order for PAR to decrease the overall intensity of the bulb must decrease.

As for fans, they are not needed, there are already plenty of LED lights for other applications which use high powered LEDs with properly designed heat sinks and no fans. It's a simple mater of cutting costs and the temperature gradient and heat transfer rate of LEDs is high and low enough respectively to eliminate the need for convective cooling. Computer components like CPUs run much hotter, their heat flux is way higher than an LED and require convective cooling. Computers are also built as cheap as possible, it's a huge commodity market.

[Ron99]

Originally Posted by sphelps

As for fans, they are not needed, there are already plenty of LED lights for other applications which use high powered LEDs with properly designed heat sinks and no fans. It's a simple mater of cutting costs and the temperature gradient and heat transfer rate of LEDs is high and low enough respectively to eliminate the need for convective cooling. Computer components like CPUs run much hotter, their heat flux is way higher than an LED and require convective cooling. Computers are also built as cheap as possible, it's a huge commodity market.

So you want a fixture that looks stylish, has a long warranty but doesn't run any fans. I'm not sure all those are compatible criteria

[sphelps]

Originally Posted by Ron99

So you want a fixture that looks stylish, has a long warranty but doesn't run any fans. I'm not sure all those are compatible criteria

Well the warranty isn't that big of a thing if the quality is obviously there. But yeah for sure on stylish with no fans, otherwise I'll stick with what actually works, looks good, is reliable and quiet. I call them Halides and like it or not they are the best all around type of lighting for the average tank, just saying

[OceanicCorals-Eugene-]

Originally Posted by sphelps

As for fans, they are not needed, there are already plenty of LED lights for other applications which use high powered LEDs with properly designed heat sinks and no fans. It's a simple mater of cutting costs and the temperature gradient and heat transfer rate of LEDs is high and low enough respectively to eliminate the need for convective cooling. Computer components like CPUs run much hotter, their heat flux is way higher than an LED and require convective cooling. Computers are also built as cheap as possible, it's a huge commodity market.

Im not so sure about that, give me an example of high power LEDs thats out there that doesn't utilize some form of active cooling, the ones found in the new Audi cars utilize passing air from inside the engine bay is a quick one that comes to mind. Its not so much cutting cost, im sure that has something to do with it, But if the heatsinks were made adequate enough for the LEDs to start the addition of fans only adds to the overall benefit of the fixture by keeping the LEDs at a much cooler temperature than without. You keep pointing out that fans have reliability issues. If you rip open one of the fixtures made for our hobby you'll quickly see that the fans they use inside to reduce cost....only costs $1-2. A Prop fan that is made by a good company usually run in the range of $10-12 and are 10x more quite than the cheap ones and push more air as well.

Also i would differ to say that computers are build as cheap as possible, at my previous job i was custom building PCs to fit the need of individual people and if you dont get into the watercooling side of things, the heatsink design + fan is really focused upon in the design of a system. The cooling of a system sometimes allows you to push that much more "juice" out of the system without getting lag. Theres only so much a heatsink can do, in other words you'll never see a top of the line computer system run without some form of active cooling on its components.

[Ron99]

The other thing to consider is weight. Using fans lets you use smaller heatsinks. I have big heatsinks in my unit that probably would have done the job without fans and the bloody fixture weights at least 50 pounds. That is heavy. If I could have found thinner or lighter heatsinks in my price range I would have gone with them.

As you say, LEDs generate less heat than a CPU but you don't have 80 CPUs on one heatsink either. Either way, if you want to run the LEDs with higher current (more output) and keep the size and weight reasonable then fans are likely necessary. if you look at the units without fans they are either using 1 watt LEDs or driving 3 watt LEDs at closer to 1 watt to minimize heat.