Light output to Heat ratio?

[chrissreef]

Setting up a small tank and I can't afford LED's

So, is there a good estimate of light/heat output ratio out there? Trying to keep from buying a small chiller while still having a TON of light.

T5? VHO? PC? MH?

Thanks!

[renisel]

In any lighting system, virtually all of the energy is converted into either light or heat. So, the more light you get per watt, the higher the light to heat ratio. People often say that MH produces more heat than fluorescents, but this is a bit deceptive. MH raises the temperature of your tank more than T5 because it is providing more light. A T5 system producing the same amount of light with a similar spectrum would raise the temperature just as much--possibly more. A portion of the light directed into your water will be absorbed by the water and converted to heat. MH produces significantly more light per watt than T5, so it causes significantly more of a temperature increase. Despite the fact that MH increases the temperature more, the T5's are still directly producing more heat (as opposed to indirect heat production by means of the water absorbing light). However, much of it is generated in the ballast, or radiated by the lights away from the tank, so that it doesn't have an effect on the tank temperature.

[NateHarris]

bump

[renisel]

In case it wasn't entirely clear in my (excessively thorough?) reply, the answer is that MH should generally give you the highest light:heat ratio; but any powerful lighting system is going to generate a substantial amount of heat because of light absorption by water.

[chrissreef]

thanks =) so basically all current light is equal except LED and there's no avoid heat =/

[gcarroll]

LED's produce heat, but the heat is displaced via active cooling. Hahnmeister or Rich (don't remember which) has always said that a metal halide system with active cooling reflectors would also displace the heat away from the tank as well.

[chrissreef]

What are these "active cooling reflectors" you speak of? any for sale? (Lum 3's?)

[renisel]

Originally posted by chrissreef
thanks =) so basically all current light is equal except LED and there's no avoid heat =/

To the best of my understanding, a set of LED's that put out as much light as halides should still cause significant heating of the water. More light equals more energy directed into the tank. The portion of that energy that is absorbed and converted into heat should be about constant, so that additional light energy translates into additional heat.

[chrissreef]

Ren;

Check out Solaris LED aquarium lighting... it's about 40% of the heat ouput of MH. I'm no scientist but I don't think "light" intensity is turned into heat... only the infra red waves turn into heat or how the actual light operates pretty much. Example - flourescent light produces much less heat than incondescent but produces much more "light"

I could be way off though or missing some basic principals... it's all pretty interesting with a lot going over my head - but as with some athletes, I'm game... win/lose or confused =P

[gcarroll]

Originally posted by chrissreef
What are these "active cooling reflectors" you speak of? any for sale? (Lum 3's?)

Luminarc III w/ A/C upgrade
Reef Optix 4 w/ OPTIONAL Air-Cooled Fittings
Reef Optix 5 w/ OPTIONAL Air-Cooled Fittings
Most people never get them because they don't want to deal with the fans and the ducting. I did see a guy though who just mounted a fan right to the Luminarcs with the cooling option. It really did do a good job of venting the heat away from the water.

[chrissreef]

Thanks - hmm, maybe we won't have to turn on our heater for the winter after all =P

[gcarroll]

No problem. Lighting will always be one of those tough choices.

[renisel]

Originally posted by chrissreef
Ren;

Check out Solaris LED aquarium lighting... it's about 40% of the heat ouput of MH. I'm no scientist but I don't think "light" intensity is turned into heat... only the infra red waves turn into heat or how the actual light operates pretty much. Example - flourescent light produces much less heat than incondescent but produces much more "light"

I could be way off though or missing some basic principals... it's all pretty interesting with a lot going over my head - but as with some athletes, I'm game... win/lose or confused =P

Since you said you find this interesting (and I'm sitting around at work with nothing better to do)...All light (visible, infrared and UV) is just electromagnetic waves, which carry energy. When these waves/photons encounter matter, they can just pass through with no interaction, or they can be absorbed. When they are absorbed, the molecules with which they collide begin to move faster (i.e. they translate the light energy into kinetic energy). Heat is simply energy stored in the form of moving molecules, and temperature is a measure of the average kinetic energy of the molecules in a substance. So, when light is absorbed by matter (as your aquarium's water absorbs light), it necessarily adds heat to the system and increases the temperature. The reason people often say that heat is infrared light is that heat is often transferred in the form of infrared light, as this long-wavelength light is absorbed (and converted into heat) by most matter.

Now, with that background info, when you put energy into a light system, virtually all of it has to be converted into light (moving photons), heat (moving molecules) or sound (which is really a form of heat, as it is just a phenomenon of moving molecules). Let's say you have two light systems with 100W input each, and your water absorbs 10% of the light, turning it into heat. Also, system A converts 90% of its energy into light, and system B converts 80% into light. From the light alone (ignoring, for a moment, the heat directly generated by each system), you get 9W of heat into your tank from system A and 8W of heat into your tank from system B. As you can see, the system that produces less heat directly actually contributes more heat to your tank--and it does so because it is more efficient and runs "cooler", not despite this fact. While system B turns 20% of its power into heat, it's very possible that much of that heat is radiated away into the air from the fixture or from a ballast that's a few feet away from the tank--so that heat doesn't translate into increased tank temperatures (this is the heat they are talking about when they say that LED's produce 40% as much heat as MH). The portion of that heat that is produced at the bulb will have a more significant impact on the tank temperatures, but I've read that fluorescents and halides produce roughly the same amount of heat at the bulb at a given wattage; but the heat is much more spread out on a fluorescent's larger bulbs, leading to cooler temperatures and the illusion of less heat.

[chrissreef]

ah thanks - that made more sense. I guess I meant more of the heat transfer from bulb to tank/room temperature.

Here's some interesting articles/reviews... some of the info confuses me =)

http://www.advancedaquarist.com/2006/8/review1

http://www.advancedaquarist.com/2006/8/review2

[BlakDuc]

Fans are much cheaper than chillers. A couple of fans running over your MH bulbs will keep them much cooler. I dont know but this might increase their lifespan as well?

[pjf]

I'd go with T5 for the highest lumens per watt at an affordable price.

• A 4-foot 115-watt T12-VHO lamp produces 49 to 55 lumens per watt (http://www.elliptipar.com/vertical/Vertpdf/VertGdLg.pdf).
• A 4-foot 54-watt T5-HO produces 93 lumens per watt (http://www.lrc.rpi.edu/programs/nlpi.../lat5/pc1a.asp).
• I don't have lumens per watts figures for metal halide lamps but the most efficient ones are high wattage commercial lamps. Generally, the low to mid-wattage (400w or less) and bluish lamps for aquariums have lower than T5 efficiency. Sanjay's Reef Lighting Pages (http://www.reeflightinginfo.arvixe.com/) has MH efficiency figures in PPFD/watts so you can get relative rankings.
• The Solaris I4 uses an 80 lumen per watt LED (http://www.solarisled.com/).
• The AquaIllumination uses a 100 lumen per watt LED (http://www.reefcentral.com/forums/sh...0#post11127402).

The reason why efficiency (lumens/watt) matters is because you want to get a lot of light (lumens) with less energy (watts).

PS - I forgot to add that reflectors are important. Individual parabolic reflectors on T5 and MH bulbs will get you far.