Power comparison of MH and t5

HV1990 · 06/07/2012, 09:33 AM

Okay so there has been some debate between a few reefers about how much heat t5's put out against MH. Now here is where I come to the masses to learn a few different opinions.

The comment was made that t5's and MH use the same efficiency. This assumption means they put out the same amount of heat. Comparing 500 watts of MH (two 250s) vs 432 watts (8 bulb t5) fixture will put out 'X' amount of heat.

I have a hard time believing this since I run a 600 watt power supply on my PC and that doesn't put out as much heat as my lights but my 36 watt processor does.

So fellow engineers reefers please chime in.

One thing I ask is please explain your logic so I can understand.

James77 · 06/07/2012, 09:59 AM

Your 600 watt power supply is sending energy elsewhere, so the only heat you feel at the power supply is the heat generated by it converting it.

Watt for watt, halides T5s and LEDs will put out the same heat. If you were to compare 500 watts of each, one may give off way more useable light, but all that light is just temprarily converted energy, and will be absorbed back into heat, or stored as energy by the animals we keep.

LEDs and T5s need fwere watts to deliver the smae amoutn of light as halides due to better efficiencies as well as easier managing of the light. T5s are a long narrow tube that can have a parabolic reflector wrapped around it. LEDs shoot their light one direction, and it is easy to use optics. Halides are a very bright, intense point of light, more difficult to reflect. They also impart more heat directly to the water through infrared heat. Also people being able to touch T5 tubes without screaming in agony like you would halides adds to theat perception of less heat. The heat is just spread out more.

Watts in, watts out. With LEDs and T5s, you are able to use less to accomplish the same....usually. But watt fro watt, they will all end up putting out the same heat in the end.

James77 · 06/07/2012, 10:01 AM

Some threads on it:

http://www.reefcentral.com/forums/sh...ht=halide+heat

http://www.reefcentral.com/forums/sh...=metal+halides

sirreal63 · 06/07/2012, 10:04 AM

In very general and completely correct terms, watts are heat. Pick the source and the outcome is always the same, 500 watts of energy are 500 watts of heat. It is basic physics. 500 watts of MH, T5, LED, water heater, electric fan, etc etc all end up as 500 watts of heat. This topic has been beat to death so many times over the years and the result is always the same.

Here is a good post that explains it a little better.
http://www.reefcentral.com/forums/sh...33&postcount=6

A 500 watt MH will put out a total of exactly 68 watts more heat than a 432 watt T5.

06/07/2012, 09:33 AM	#1
HV1990 Registered Member Join Date: Apr 2010 Location: Sacramento CA Posts: 1,964	Power comparison of MH and t5 Okay so there has been some debate between a few reefers about how much heat t5's put out against MH. Now here is where I come to the masses to learn a few different opinions. The comment was made that t5's and MH use the same efficiency. This assumption means they put out the same amount of heat. Comparing 500 watts of MH (two 250s) vs 432 watts (8 bulb t5) fixture will put out 'X' amount of heat. I have a hard time believing this since I run a 600 watt power supply on my PC and that doesn't put out as much heat as my lights but my 36 watt processor does. So fellow engineers reefers please chime in. One thing I ask is please explain your logic so I can understand. __________________ 120g AGA Tank, 2 Lumenarc Mini w/ 250w Radiums on select-a-watt ballast 2 t5 actinics. Lighting controlled via Apex Jr controller. Carbon and GFO in TLF reactors, 7 gallon Refugium, Cooling by 8 1 Current Tank Info: 120g Mixed reef tank

06/07/2012, 09:59 AM	#2
James77 Registered Member Join Date: Aug 2005 Location: Rhode Island Posts: 8,158	Your 600 watt power supply is sending energy elsewhere, so the only heat you feel at the power supply is the heat generated by it converting it. Watt for watt, halides T5s and LEDs will put out the same heat. If you were to compare 500 watts of each, one may give off way more useable light, but all that light is just temprarily converted energy, and will be absorbed back into heat, or stored as energy by the animals we keep. LEDs and T5s need fwere watts to deliver the smae amoutn of light as halides due to better efficiencies as well as easier managing of the light. T5s are a long narrow tube that can have a parabolic reflector wrapped around it. LEDs shoot their light one direction, and it is easy to use optics. Halides are a very bright, intense point of light, more difficult to reflect. They also impart more heat directly to the water through infrared heat. Also people being able to touch T5 tubes without screaming in agony like you would halides adds to theat perception of less heat. The heat is just spread out more. Watts in, watts out. With LEDs and T5s, you are able to use less to accomplish the same....usually. But watt fro watt, they will all end up putting out the same heat in the end. __________________ Jim Current Tank Info: 120g Mixed Reef and 75g Freshwater

06/07/2012, 10:01 AM	#3
James77 Registered Member Join Date: Aug 2005 Location: Rhode Island Posts: 8,158	Some threads on it: http://www.reefcentral.com/forums/sh...ht=halide+heat http://www.reefcentral.com/forums/sh...=metal+halides __________________ Jim Current Tank Info: 120g Mixed Reef and 75g Freshwater

06/07/2012, 10:04 AM	#4
sirreal63 Go Spurs Go!!! Join Date: Dec 2004 Location: Meadowlakes Texas Posts: 13,357	In very general and completely correct terms, watts are heat. Pick the source and the outcome is always the same, 500 watts of energy are 500 watts of heat. It is basic physics. 500 watts of MH, T5, LED, water heater, electric fan, etc etc all end up as 500 watts of heat. This topic has been beat to death so many times over the years and the result is always the same. Here is a good post that explains it a little better. http://www.reefcentral.com/forums/sh...33&postcount=6 A 500 watt MH will put out a total of exactly 68 watts more heat than a 432 watt T5. __________________ 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.