540w T5 vs 500w metal halide heat comparison??

Cathman · 01/23/2015, 06:21 PM

As questioned. Would these two options not disperse a similar amount of heat being wattage is close to same? I know that metal halide is more focal being that it's a single point source. And t5 is spread over the lengths of the bulbs so they don't seem as hot. But has anyone done a true measurement of total heat dissipated overall. Hope that makes sense. I'm trying to decide between two 250w halide was a ten bulb t5 fixture to cover my 48x36x22 tank.

sirreal63 · 01/23/2015, 06:39 PM

The T5 will put out about 40 watts more heat. That is not 100% accurate because the ballasts also put out heat. The trick is to move that heat away from the water surface.

Cathman · 01/23/2015, 08:54 PM

Ok, not saying you're wrong but i realize heat is a byproduct of several things...i believe in lighting it is related to efficiency. I am looking for real evidence as I have seen many people go from metal halide to T5 for the reason of heat. Yet that still leads me back to the original question. Are T5 of the same wattage amount more efficient and actually produce less total heat, or does is seem this way becuase the heat generated is over a larges surface area therefor its dissipated better and gives us the false sense they run cooler.

The room my tank is in is at the end of my A/C duct. Therefore it is always warmer in this room compared to the set thermostat or rest of the house.

So, if the same amount of heat overall is generated by either system, i would prefer to go the metal halide route. I know they both work, but bulb replacement for two metal halides versus 10 T5 seems like it would get pricey.

sirreal63 · 01/23/2015, 08:57 PM

The T5's are producing more light for the same wattage, it is because they are more efficient, yet with equal wattage the heat is the same. 500 watts is 500 watts of heat no matter what the source, efficiency has nothing to do with the wattage producing heat. T5's offer the ability to get the same amount of light with less wattage. Does that make sense?

JBinFla · 01/23/2015, 10:29 PM

Is it not safe to say that 500w is 500w, whether it's heat or light but it can't be 500w of heat and light...

sooo... 500w more efficient light would produce less heat (more wattage going to light, not heat)

Or am I missing something?

sirreal63 · 01/23/2015, 10:49 PM

Light is also heat and why cannot there be both light and heat? Look at any light source, there is both light and heat. The efficiency is irrelevant here, 500 watts is 500 watts of energy. A more efficient unit will emit more light per watt than a less efficient one, so you do not need as many watts, but if the wattage is the same, the heat is the same.

JBinFla · 01/24/2015, 11:58 AM

It's been a while since I took thermodynamics, but I'm pretty sure light and heat are two different forms of energy. If the energy is fixed (in watt/hrs or whatever you want to use) then the more that goes to light leaves less for heat. The two are not one in the same. Both forms of energy, yes, but not the same form and converting energy from a fixed output source into one form, leaves less energy for the other forms. That is a basic law of physics, I'm not making this stuff up. However, as my experience with aquarium lighting is in fact limited, I will step aside since my understanding of this topic stops at physics, thermodynamics and their applied mathematics.

- Joe

sirreal63 · 01/24/2015, 12:20 PM

Look up cold light and incandescence. Our lighting users incandescence, not luminescence. I challenge you to find a light that uses electricity that the light itself has no heat associated with it. For the OP's needs, the heat is about the same, with the T5 putting out about 40 watts more heat.

Your physics lesson is mostly irrelevant here, it doesn't apply. The end product of energy usage is heat, whether it be from light, motion or friction, 500 watts ends up being 500 watts of heat, no matter what form it is converted to, the end product is always the same, heat, even if it is stored, the stored energy will eventually be heat when used.

nibor75 · 01/24/2015, 12:27 PM

+1 sirreal63

The process does not stop there, the radiant energy (IR, UV and visible light) also ultimately become heat.

A 250W LED or T5 light will heat the room just as much as a 250W halide light. That does not mean that the aquarium would be heated the same amount. The light source with the least radiant energy being transmitted to the tank heats the water the least. The rest of the energy heats the surrounding environment.

Cathman · 01/24/2015, 02:28 PM

So regardless of what source i go with the room will be heated the same. Conservation of energy law has nothing to do with this....meaning if more of the electricity if converted to light (fluorescent) vs heat (halide) wouldn't the T5 create less emitted heat overall?

If not, then why do i see so many folks switch from halide to T5 due to heat. Why not just raise the light enough, blow a fan under and across to carry the heat away from the surface and use halide all the time? I realize that distance is a factor for amount of par transmitted, but when through air, the reduction is minimal i would think (by far not an expert on this).

I'm stuck because i think i would need 10 T5 bulbs to cover the 36" deep tank i have, and i think that 2 halides would be pretty dang close coverage wise and would put the lower light needing corals on the outer edges...although the way i have set up my rock its in a horseshoe shape facing front so the fish have open swimming room all around the tank...the rock is about 5" from the back wall...does not touch and about the same for the front...so most would be in the outer edges lit very well still.

sirreal63 · 01/24/2015, 03:23 PM

I actually had more heat issues in the past with T5's than MH, it depends on how well you ventilate. You are correct that in the scenario you presented they will both heat the room about the same. You have to decide if you want a nice reef or a cool room, though you may be able to have both. Limit the submerged wattage, it is usually as much of a heat source as lights, and use the lights you think will do the job the best. In this case, either will do the job so focus your energy (so to speak) on the rest of the setup and make it as efficient as possible.

If you use a canopy, make it open top and allow air flow from around the perimeter where it sits on the tank, that way it will draw air up from the bottom of the canopy and exhaust it out the top. Heat rises so use that to your advantage.

01/23/2015, 06:21 PM	#1
Cathman Super Ninja Reefer Join Date: May 2006 Location: Yep, Texas Posts: 142	540w T5 vs 500w metal halide heat comparison?? As questioned. Would these two options not disperse a similar amount of heat being wattage is close to same? I know that metal halide is more focal being that it's a single point source. And t5 is spread over the lengths of the bulbs so they don't seem as hot. But has anyone done a true measurement of total heat dissipated overall. Hope that makes sense. I'm trying to decide between two 250w halide was a ten bulb t5 fixture to cover my 48x36x22 tank.

01/23/2015, 06:39 PM	#2
sirreal63 Go Spurs Go!!! Join Date: Dec 2004 Location: Meadowlakes Texas Posts: 13,357	The T5 will put out about 40 watts more heat. That is not 100% accurate because the ballasts also put out heat. The trick is to move that heat away from the water surface. __________________ Jack No One has ever been seriously injured by using the search function. Alcohol, Tobacco and Firearms should be a convenience store, not a government agency. Current Tank Info: Reefing the Pentagon.

01/23/2015, 08:57 PM	#4
sirreal63 Go Spurs Go!!! Join Date: Dec 2004 Location: Meadowlakes Texas Posts: 13,357	The T5's are producing more light for the same wattage, it is because they are more efficient, yet with equal wattage the heat is the same. 500 watts is 500 watts of heat no matter what the source, efficiency has nothing to do with the wattage producing heat. T5's offer the ability to get the same amount of light with less wattage. Does that make sense? __________________ Jack No One has ever been seriously injured by using the search function. Alcohol, Tobacco and Firearms should be a convenience store, not a government agency. Current Tank Info: Reefing the Pentagon.

01/23/2015, 10:49 PM	#6
sirreal63 Go Spurs Go!!! Join Date: Dec 2004 Location: Meadowlakes Texas Posts: 13,357	Light is also heat and why cannot there be both light and heat? Look at any light source, there is both light and heat. The efficiency is irrelevant here, 500 watts is 500 watts of energy. A more efficient unit will emit more light per watt than a less efficient one, so you do not need as many watts, but if the wattage is the same, the heat is the same. __________________ Jack No One has ever been seriously injured by using the search function. Alcohol, Tobacco and Firearms should be a convenience store, not a government agency. Current Tank Info: Reefing the Pentagon.

01/24/2015, 12:20 PM	#8
sirreal63 Go Spurs Go!!! Join Date: Dec 2004 Location: Meadowlakes Texas Posts: 13,357	Look up cold light and incandescence. Our lighting users incandescence, not luminescence. I challenge you to find a light that uses electricity that the light itself has no heat associated with it. For the OP's needs, the heat is about the same, with the T5 putting out about 40 watts more heat. Your physics lesson is mostly irrelevant here, it doesn't apply. The end product of energy usage is heat, whether it be from light, motion or friction, 500 watts ends up being 500 watts of heat, no matter what form it is converted to, the end product is always the same, heat, even if it is stored, the stored energy will eventually be heat when used. __________________ Jack No One has ever been seriously injured by using the search function. Alcohol, Tobacco and Firearms should be a convenience store, not a government agency. Current Tank Info: Reefing the Pentagon.

01/23/2015, 08:54 PM	#3
Cathman Super Ninja Reefer Join Date: May 2006 Location: Yep, Texas Posts: 142	Ok, not saying you're wrong but i realize heat is a byproduct of several things...i believe in lighting it is related to efficiency. I am looking for real evidence as I have seen many people go from metal halide to T5 for the reason of heat. Yet that still leads me back to the original question. Are T5 of the same wattage amount more efficient and actually produce less total heat, or does is seem this way becuase the heat generated is over a larges surface area therefor its dissipated better and gives us the false sense they run cooler. The room my tank is in is at the end of my A/C duct. Therefore it is always warmer in this room compared to the set thermostat or rest of the house. So, if the same amount of heat overall is generated by either system, i would prefer to go the metal halide route. I know they both work, but bulb replacement for two metal halides versus 10 T5 seems like it would get pricey.

01/23/2015, 10:29 PM	#5
JBinFla Registered Member Join Date: Jan 2015 Location: Wesley Chapel, FL Posts: 37	Is it not safe to say that 500w is 500w, whether it's heat or light but it can't be 500w of heat and light... sooo... 500w more efficient light would produce less heat (more wattage going to light, not heat) Or am I missing something?

01/24/2015, 11:58 AM	#7
JBinFla Registered Member Join Date: Jan 2015 Location: Wesley Chapel, FL Posts: 37	It's been a while since I took thermodynamics, but I'm pretty sure light and heat are two different forms of energy. If the energy is fixed (in watt/hrs or whatever you want to use) then the more that goes to light leaves less for heat. The two are not one in the same. Both forms of energy, yes, but not the same form and converting energy from a fixed output source into one form, leaves less energy for the other forms. That is a basic law of physics, I'm not making this stuff up. However, as my experience with aquarium lighting is in fact limited, I will step aside since my understanding of this topic stops at physics, thermodynamics and their applied mathematics. - Joe

01/24/2015, 12:27 PM	#9
nibor75 Registered Member Join Date: Feb 2009 Location: French Riviera Posts: 54	+1 sirreal63 The process does not stop there, the radiant energy (IR, UV and visible light) also ultimately become heat. A 250W LED or T5 light will heat the room just as much as a 250W halide light. That does not mean that the aquarium would be heated the same amount. The light source with the least radiant energy being transmitted to the tank heats the water the least. The rest of the energy heats the surrounding environment.

01/24/2015, 02:28 PM	#10
Cathman Super Ninja Reefer Join Date: May 2006 Location: Yep, Texas Posts: 142	So regardless of what source i go with the room will be heated the same. Conservation of energy law has nothing to do with this....meaning if more of the electricity if converted to light (fluorescent) vs heat (halide) wouldn't the T5 create less emitted heat overall? If not, then why do i see so many folks switch from halide to T5 due to heat. Why not just raise the light enough, blow a fan under and across to carry the heat away from the surface and use halide all the time? I realize that distance is a factor for amount of par transmitted, but when through air, the reduction is minimal i would think (by far not an expert on this). I'm stuck because i think i would need 10 T5 bulbs to cover the 36" deep tank i have, and i think that 2 halides would be pretty dang close coverage wise and would put the lower light needing corals on the outer edges...although the way i have set up my rock its in a horseshoe shape facing front so the fish have open swimming room all around the tank...the rock is about 5" from the back wall...does not touch and about the same for the front...so most would be in the outer edges lit very well still.

01/24/2015, 03:23 PM	#11
sirreal63 Go Spurs Go!!! Join Date: Dec 2004 Location: Meadowlakes Texas Posts: 13,357	I actually had more heat issues in the past with T5's than MH, it depends on how well you ventilate. You are correct that in the scenario you presented they will both heat the room about the same. You have to decide if you want a nice reef or a cool room, though you may be able to have both. Limit the submerged wattage, it is usually as much of a heat source as lights, and use the lights you think will do the job the best. In this case, either will do the job so focus your energy (so to speak) on the rest of the setup and make it as efficient as possible. If you use a canopy, make it open top and allow air flow from around the perimeter where it sits on the tank, that way it will draw air up from the bottom of the canopy and exhaust it out the top. Heat rises so use that to your advantage. __________________ Jack No One has ever been seriously injured by using the search function. Alcohol, Tobacco and Firearms should be a convenience store, not a government agency. Current Tank Info: Reefing the Pentagon.