Are LED lights hot?

[wabooth555]

I keep reading that some people who've upgraded to LEDs are having a tougher time controlling heat. I was under the impression that LEDs are not hot.

I plan on upgrading lights on my BioCube 29 to 24 LEDs via RapidLED. The BioCube 29 is completely enclosed. I don't have a heat issue now, but will I if I upgrade?

[James77]

Not sure where you are reading that? Everyone I have seen that was struggling with heat had the problem alleviated by going to LEDs. What wattage lighting do you have right now. If it is completely enclosed, compare the watts of the LEDs you want to the watts of the lights you have now. Watts are watts, 25 watts of LEDs will produce the same heat as 25 watts of compact fluorescents......so that is a good way to gauge whether the tank will run cooler or warmest.

[bluewater921]

i run LEDs and my tank runs 78 to 79 during the day .. when i had T5s and MHs i would run during the day 82 to 83 .. i think im running a lot cooler ..

[wabooth555]

ok, must have been confused. I'm glad to hear your replies. thanks souch. I feel much better now.


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[wabooth555]

ok, must have been confused. I'm glad to hear your replies. thanks souch. I feel much better now.


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[ggrillo]

LEDs themselves get very hot for their size, that's why all the DIYers must attach large heatsinks and fans. The heat does not compare to MHs or T5s though. LEDs also need to be kept cool in order to run properly. So these heat issues you may have been hearing about are most likely issues with the lights themselves vs heat in the tank.

[Anemonebuff]

I dropped from 605 watts of MH to about 150 watts of LED. I no longer need to run my A/C in the basement to make it liveable for me or the tank.

[jerpa]

I dropped from 605 watts of MH to about 150 watts of LED. I no longer need to run my A/C in the basement to make it liveable for me or the tank.

That is where you reduce the heat, by reducing the wattage. LEDs produce a lot of heat in a very small area, hence the need for heatsink and fans.

[BigAl2007]

LED themselves are hot but the heat is on the back of the diode and not transferred into the water unlike MH and other light options. The heat has to be taken away from the DIODE for performance and life-span which is why you see large Heat Sinks on all LED fixtures (or at least the ones that will last a while). Don't think that LED do NOT produce heat because they do and a good amount of it but.... because they are using less electricity and are prroducing the heat in a different way the tank "in general" runs cooler. There are exceptions to this but for the most part this is the case.

With this being said my LED units (which both have a good size heat sink) get hot but even at 100% power I can still lay a bare hand on the heatsink and not get burned. It's HOT to the touch but no burning etc. Not like if you touch a piece of skin to a MH bulb for sure.

[pk_hk]

Watts are a unit of power and essentially heat produced by circuitry, not a measure of light.

[wabooth555]

OK, so I wasn't going completely crazy. This makes a lot of sense now. Thank all for clearing this up for me.

[James77]

even at 100% power I can still lay a bare hand on the heatsink and not get burned. It's HOT to the touch but no burning etc. Not like if you touch a piece of skin to a MH bulb for sure.

Because the wattage of the LEDs are spread over a much larger area. Yes, less watts in total are used. However, concentrate all those watts into the same area as a halide bulb takes up, you will get burned. Halides produce a single very bright point of light and use large reflectors to spread. LEDs are a much smaller, weaker point, but you use much more of them.

[WingoLED]

As any lighting device, the device itself will get warm up and, if not dissipated, will become hot.

Heat transferred to water where the light shines is minimal with LED because LED is very specific to its advertised spectrum and thus no extra spectrum generated by most other lighting technology will not be generated such as thermal radial energy will present. That is, even though we don't see the heat energy going to the water, we can still feel it with our hands. Place your hand 12" in front of the MH and then a LED, you can tell. However, LED is not 100% efficient in converting electricity to light energy, by conservation of energy law, some energy not converted to light turns into some other form energy which in this case is thermal energy again. This is mostly radiated thru the back of the leds and then to the heat sink... The total heat energy generated by LED vs MH is much less because LED has a higher light converting efficiency. So matter how you measure it, LED is cooler than MH in every aspect for the same amount of energy(wattage) you run them at.

[jerpa]

The total heat energy generated by LED vs MH is much less because LED has a higher light converting efficiency.

LEDs are very efficient at creating light of a specific spectrum, however they are not efficient in terms of power in compared to light output. They are actually quite inefficient. I hope Bean doesnt mind me borrowing the graphic he found.

http://www.reeflogix.com/images/rc/whitelight_new.jpg

As you can see LEDs are quite comparable to MH in terms of visible light output per watt. Where they gain efficiency is in their ability to direct the light they generate and the ability to produce a remarkable amount of light within a narrow spectrum. This allows us to increase intensity in the areas needed for photosynthesis without increasing the energy used producing other kinds of light. The lack of IR output does reduce the heat being introduced to the tank.

[James77]

The total heat energy generated by LED vs MH is much less because LED has a higher light converting efficiency. So matter how you measure it, LED is cooler than MH in every aspect for the same amount of energy(wattage) you run them at.

Watt for watt in terms of total heat they are identical. Yes, a lot less heat may be transferred to the tank in terms of IR, but the heat still ends up in the room. Even if LEDs converted 50% of their energy into light, it is only temporary. That is where the conservation of energy comes into play, energy cannot be destroyed. So after the LED converts it to light, it will be absorbed as heat once it strikes an object, aside from the trivial amount absorbed by algae and coral ( hopefully more coral than algae :) ). Again, that is watt for watt, but you usually need substantially fewer watts of LEDs over most tanks.....that combined with the little or non existant IR from LEDs is the reason why they are cooler. But 150 watts of LED will give off the same amount of heat as 150 watts of halides, just to different areas(ie directly to the room or tank)

[Tickle]

I think you would maybe run into problems if you had the heatsink mounted in your hood and didnt have.proper ventillation. I know my leds kick off a good amount of heat. My heatsinks are externally mounted so all the heat is dissapated into the air vs into the canopy. Just some food for thought.

the phone in my hands

[Mmiller40gt]

I keep reading that some people who've upgraded to LEDs are having a tougher time controlling heat. I was under the impression that LEDs are not hot.

I plan on upgrading lights on my BioCube 29 to 24 LEDs via RapidLED. The BioCube 29 is completely enclosed. I don't have a heat issue now, but will I if I upgrade?

Your have an enclosed hood so you will see a heat increase as you are increasing the wattage with the rapid kit. Doubt its enough to make a difference unless your house is warm. I have the 28 HQI 150 and it needs a chiller to stay cool.

[WingoLED]

Thanks for clearing up the part that I omitted as I am preoccupied with assumption that we are talking about reef aquarium application and the major heat lowering(in our case) is due to the fact that we don't need to use as much power as the other lighting technology to generate the same amount of useful light for our reef.

[ddawson]

I have a BC 14 with 19 LEDs under the hood with no temp issues. The hood does get a little warm but not hot.

[s60rfrank]

LEDs run cooler for sure

[nynick]

Simple answer without charts and need for calculator :)

With MH, my tank ran at 82-84 during day and heater NEVER came on. With LED it runs at 78, for now...might lower it further, and heater comes on all the time. It runs a LOT cooler for all practical purposes.

[djd]

Humm so your energy savings are out the window if now as you say the water heaters come on alot more !
After all corals grow fast at 80f to 84f comparied to say 78 f = your having to heat the water now with a seperate heater vs MH
kinda flys in the face of the LED hype ! , albeit Leds dont shift spectrum like MH do = Big +
so no real enery savings with LED system wise
one more comment on a reply advising/ commenting on switched out 600 watts of MH to 120 watts of LED ????
I find this very hard to believe unless didnt really need the 600 w of MH in the first place

[nynick]

I am sorry Djd but I have no idea what you are trying to say beyond the first sentence.

The heater pops on and off on occasion (guesstimate 2 hours a day, tops) and is 200w. My total LED is 240w but running just over 50% so 140w to be generous. Compared to a constant 600w it is still a considerable saving on electricity.

[jerpa]

Humm so your energy savings are out the window if now as you say the water heaters come on alot more !
After all corals grow fast at 80f to 84f comparied to say 78 f = your having to heat the water now with a seperate heater vs MH
kinda flys in the face of the LED hype ! , albeit Leds dont shift spectrum like MH do = Big +
so no real enery savings with LED system wise
one more comment on a reply advising/ commenting on switched out 600 watts of MH to 120 watts of LED ????
I find this very hard to believe unless didnt really need the 600 w of MH in the first place

These are all factors people need to consider when switching. You can't simply subtract the difference in watts to figure your savings. However a heater will heat a tank more efficiently than a MH light. You aren't using the same watts to heat the water that you are eliminating by switching to LEDs. You also have to factor in a chiller running less if you have one. With the electric rates of most of the country fairly low the payback on LED comes more from bulb replacement. Even $5 a month will still be several hundred dollars over the expected life of the fixture though.

[djd]

Thanks Jer
You cleared up nicely ... Energy saving questionable or not as big as all the advertising would have me believe !
Real savings are in no Bulb change outs

Cheers

[James77]

I had that when I had my LEDs.....my heater ran that much more directly becuase of swithcing ot LEDs. But LEDs will allow using the bare minimum of watts to heat the tank, as opposed to halides running it a couple degrees over depending on the setup. I need all the heat I can get, and my electric savings strictly on light usage from LEDs are less than 10 bucks a month. So having the heater on quite a bit more ( I had graphed it when I switched) ate away a good chunk of those savings. So for me, it was just another point to halides since I prefer the look of them anyways.

Bulb savings are pretty trivial in my opinion, but I also use LEDs for actinic supps so again I am not seeing as mcuh savings as something jumping from VHO/T5 and 400 watt halides into 100% LEDs. VHOs are stupidly expensive, and they use a good amount of electric and I dont miss them. For me replacing halide bulbs once a year at prices ranging from $90 for 2 Phoenix up to $140 for 2 radiums is not really a big deal. Lets not forget that we are also basing the LED savings on nothing going wrong. Especially for finished commercial fixtures like Sol and Radion, thing will potentially fail out of warranty over the expected life. It may not happen, or it may happen a lot....it is an unknown. But I'd be a little concerned that replacement parts for these current LED fixtures might not be around in 5 years seeign as how there is a new fixture every year. Not sure if these companies are future proofing any of these though.

[djd]

Well that sums it up then and my mind !

I'm staying with MH !

Thanks for clearing up the / my remaining doubts

This forum rocks !

[jerpa]

I can honestly say that I would never switch to LEDs to save money. In the grand scheme of things electricity savings and bulbs are the cheaper aspects of this hobby. I consider the dollars I'm saving a bonus. Of course none of this would apply if I lived in California...

I also like the look of my LEDs however. I ran MH for a year on my first tank before switching and I can honestly say I like MH and led pendant lighting just about equally. Not so much the typical LED fixtures but to each their own.

[nynick]

The best part of led lights for me isn't the savings at all, it is how neat the space under my tank is all of a sudden :) I think they might end up costing me a lot more than the electricity savings since I now have room for a refugium where all the T5 and MH stuff was :)

[Narwhal82]

I think this may have already been said but just in case anyone is still confused.

LED's do produce quite a bit of heat but it is conductive heat not radiant heat. Conductive heat requires a conductor to channel the heat away from the diode (air is not a good conductor of heat). This is often in the form of an aluminum heat sink that is connected to the PC board with thermal grease or adhesive. If the heat is not conducted away from the diode the diode overheats and burns out. Especially in higher powered diodes, heat managment becomes critical. Otherwise you are going to be replacing a lot of chips which will get very expensive very quickly.

A metal halide lamp produces a high degree of radiant heat. Radiant heat heats up the area surfaces around it mainly by the conversion of Infrared energy to heat as it impacts a surface. This is why aquariums heat up under halides but not LED's.

Both types of systems require heat management. LED's need heat management to keep the LED's cool and functioning. Halide systems need heat management to keep the water cool.

Andy

[Mmiller40gt]

Humm so your energy savings are out the window if now as you say the water heaters come on alot more !
After all corals grow fast at 80f to 84f comparied to say 78 f = your having to heat the water now with a seperate heater vs MH
kinda flys in the face of the LED hype ! , albeit Leds dont shift spectrum like MH do = Big +
so no real enery savings with LED system wise
one more comment on a reply advising/ commenting on switched out 600 watts of MH to 120 watts of LED ????
I find this very hard to believe unless didnt really need the 600 w of MH in the first place

80-84 is faster? I never considered a higher temp would enhance growth. Maybe I need to bump my chiller up a few degrees. Might save me some $$ too.

[Fryman]

LEDs are very efficient at creating light of a specific spectrum, however they are not efficient in terms of power in compared to light output. They are actually quite inefficient. I hope Bean doesnt mind me borrowing the graphic he found.

http://www.reeflogix.com/images/rc/whitelight_new.jpg

As you can see LEDs are quite comparable to MH in terms of visible light output per watt. Where they gain efficiency is in their ability to direct the light they generate and the ability to produce a remarkable amount of light within a narrow spectrum. This allows us to increase intensity in the areas needed for photosynthesis without increasing the energy used producing other kinds of light. The lack of IR output does reduce the heat being introduced to the tank.

That chart appears to be intended for a different audience, and is very misleading for our intended use.

Aquarium lighting is intended to produce light in the visible spectrum; or more specifically "Photosynthetically active radiation" or PAR. Other types of "radiant energy" such as IR and UV are wasted, or possibly just contribute to heat.

In our application, MHs transfer the most heat/watt into the water, followed by fluorescent and at the lowest end LEDs. Extra heat is usually unwanted, but in some circumstances may actually be beneficial. For instance, if the ambient temp is very cold, MHs may supplement the heaters and thus actually decrease your electric bill.

But most people have the problem of MHs heating the water beyond acceptable temps, and then have to run chillers to bring it back down.

[nynick]

Don't think you can say that 82-84 degrees will increase coral growth any more than you can say that full sun will increase plant growth. Some might like it, some might not. Way too many different types to generalize.

I have never been to the tropics and taken a dip in 84 degree water though, it tends to stay between 74 and 80 so that is what I would like my tank to be. A couple of degrees cooler (or so, didn't swim with a thermometer) just 2 or 3 yards down where you can still see plenty of corals. Having said that, I am sure there are varieties from shallow, low flow areas that would just love 84 degrees.

[James77]

That chart appears to be intended for a different audience, and is very misleading for our intended use..


It is not really misleading at all, it is just stating facts on the different lighting. It is pretty apparent that the IR is way higher with halides than LEDs, the chart shows that. That chart is only posted here to show that LEDs do indeed give off a substantial amount of heat.....since a lot of people state or are under the impression that LEDs create no heat. They do add less heat to the aquarium directly.

[James77]

Both types of systems require heat management. LED's need heat management to keep the LED's cool and functioning. Halide systems need heat management to keep the water cool.


Yes.

Halide heat is not all that hard to manage. If you put cheap crappy reflectors 6 inches off the water, or seal them in an unvented canopy, you are going to have quick heat problems. Use a higher end reflector that can be hung 12-18" off the water and/or vent hot air out of a sealed canopy, and that solves quite a few heat problems.

[Narwhal82]

I think that what was trying to be expressed by the chart is that LED's do indeed produce heat. About 70-80% of their energy input is turned into heat which makes them actually the same or less efficient than halide at converting electrical energy into usable light. Most metal halide lamps are 100 lumens per watt or better. Only some of the highest quality LED chips are higher than 100 lumens per watt. Most are in the 70-90 lumen per watt range at 350 milliamps.

The chart does not separate conductive vs. convection heat however which is the big difference between halide and LED in terms of heat as I wrote in my earlier post.

Andy

[djd]

Re Question on corals growth {faster}

Most SPS do best At 84-86 F

I ref article from Dr Ronald Shimek

"what temp should i keep my corals at "? .. then the answer is 84 F
If the question is , "what temp should I keep my tank at "?
then the answer may differ.

Anyway i'm not going to hyjack this thread

Do some reading up as i did ! .. sure changed my chiller/ heater settings
Any my coral are happy campers .. fish more active as well

[Fryman]

I think that what was trying to be expressed by the chart is that LED's do indeed produce heat. About 70-80% of their energy input is turned into heat which makes them actually the same or less efficient than halide at converting electrical energy into usable light. Most metal halide lamps are 100 lumens per watt or better. Only some of the highest quality LED chips are higher than 100 lumens per watt. Most are in the 70-90 lumen per watt range at 350 milliamps.

If that were true then we'd need the same # of watts when using LEDs or MH lighting. That is not the case.

People generally use 500-800 watts of MH (2 x 250 or 400W bulbs) over a 4 ft aquarium. If you used that much wattage in LEDs, you'd fry everything. You would generally use 6-8 T5s over the same area, which is 324 - 432 watts in T5s. For LEDs, most are recommending <250 watts of LEDs over the same area. Either the chart is out-of-date, or is simply not relevant for this application.

LEDs are significantly more efficient in terms of watts / PAR than MHs and even T5s. LEDs have the potential to be MUCH better in terms of efficiency, but even with current technology they are definitely the most efficient type of lighting.

I'm not trying to bash MHs, they are the current gold standard in reef lighting IMHO and LEDs aren't there yet. But there's a reason everyone is moving towards using LEDs now, LEDs have a lot of potential.

[jerpa]

If that were true then we'd need the same # of watts when using LEDs or MH lighting. That is not the case.

People generally use 500-800 watts of MH (2 x 250 or 400W bulbs) over a 4 ft aquarium. If you used that much wattage in LEDs, you'd fry everything. You would generally use 6-8 T5s over the same area, which is 324 - 432 watts in T5s. For LEDs, most are recommending <250 watts of LEDs over the same area. Either the chart is out-of-date, or is simply not relevant for this application.

LEDs are significantly more efficient in terms of watts / PAR than MHs and even T5s. LEDs have the potential to be MUCH better in terms of efficiency, but even with current technology they are definitely the most efficient type of lighting.

I'm not trying to bash MHs, they are the current gold standard in reef lighting IMHO and LEDs aren't there yet. But there's a reason everyone is moving towards using LEDs now, LEDs have a lot of potential.

I think your misunderstanding my statement. LEDs provide almost the same visible light output per watt as halides. We gain efficiency because we are able to direct the light without reflectors and also because we can focus the light across the spectrums we deem most necessary and decrease the intensity in wavelengths needed only for aesthetic appeal. I have no doubt LEDs will become more efficient with time but the fact remains they aren't that much more efficient at creating visible light. Watt for watt a halide produces about the same visible light as an LED. The halide just produces it across the entire visible spectrum. LEDs are more efficient because certain characteristics allow them to be used more efficiently for our purpose. They have advantages completely unrelated to efficiency such as lower radiant energy.

[Fryman]

Yes, I was focused on the chart. I see what you are saying now, and you aren't wrong. What I objected to was the way the chart is presented. The chart highlights "heat" for LEDs as the highest percentage-wise by far. Also this is highlighted in RED (everyone knows red = BAD, right?). It makes it appear that LEDs will add the most "heat", followed by flourescent, then MH, and finally incandescent. In practice, it's the reverse of that order in terms of which technology used will transfer the most heat into an aquarium!

Many people reading this forum are not familiar with the difference between conduction, convection & radiation. The chart highlights something largely inconsequential to consumers, except maybe for those who design their own lighting fixtures. Even then it's missing a lot of relevant information you hinted at yourself such as light direction, spread & spectrum.

That's why I said the chart is misleading. I don't think it's intentional, just that the chart seems to have been made to highlight something that's not really an important consideration for the majority of people reading this forum. Even comparing lumens/watt isn't giving the whole story. MH may produce as much visible light/watt as LEDs in theory, but a significant portion of that light is wasted in practice. MH lighting consumes more energy than an "equivalent" LED lighting setup. Whether they would be truly equivalent is a whole other can-o-worms...

Maybe I have deviated from the OPs question. Are LEDs hot? Yes. But they don't transfer much of this heat into the aquarium, so heat is less of a concern than with other types of lighting. Don't shy away from LEDs because of heat, that's usually considered a benefit of going with LEDs.

Again, I'm not "anti-MH" or "pro-LED". Actually, the lighting setups I thought looked the best in recent memory had MH bulbs supplemented with blue LED/actinics ;)