Originally Posted by james67
not necessarily true. there are ways (albeit not what anyone here will likley do) to keep ALL heat from lighting out of the tank while minimally affecting light intensity.
usually this requires a space between an enclosed light and the tank with lage amounts of cool air being constantly passed across the light.
I'm not sure thats true because light itself is energy and gives off heat. Take the suns rays for example, even though the sun is way far away and the air outside is 40F the sun's rays through green house glass heats the green house. Also causes my mobile home to heat up to 80 when its 50 outside and the AC isn't on. Lasers do the same thing, the light burns...not the excess power not being coverted to light and given off as heat (although that may burn you too). I wasn't sure "radiant enery" was the right term but according to wiki it appears to be. Radiant energy - Wikipedia, the free encyclopedia
He is correct, we do get some heating from radiant energy, just like the suns rays passing through a window on a cold day...and thats why they say keep your viv away from a window. Electric lights do it on smaller scale but with the glass acting as insulation and the heat trapped due to a lack of ventilation you get heat build up. You would basically need to create a vacuum inside your viv to prevent this, and even that may not work. I'd have to refresh my physics knowledge to say for sure
Fluorescents are a "colder" light source though so I don't think they have much radiant energy but I don't think they are 100% cold light (Yes cold light is an actual term). The problem is the further you move the light to reduce radiant energy and the heat given off from unconverted power the less light you get...so you need an insulator like a very clear very thick piece of glass (fans and and cool room temps allow for a thinner insulator) to eliminate almost all heat transfer leaving the very minimal radiant energy from the light only, or close to it...so while James is still correct that in using cold light sources like fluorescents you can eliminate most of the heat...perhaps all. Basically you can get so close that its is dispersed before it builds up.
So from a technical stand point Jame's is mistaken, from a practical one he is right or pretty close.
Ok another edit...I just looked again at the wiki..."watt" is "radiant energy per unit time, also called radiant power". If I read that right and understand the implications, it means all light of the same wattage gives off the same radiant energy? Eh we need a physics guru to straighten this out.
I guess the question is given the intensity of our lights is radiant energy even worth considering? (more likely it is for metal halide and other types of light other then fluorescent and led which are "colder" unless was right about all light of the same wattage having the same radiant energy, of course wave length may determine the amount of that energy also, like an IR heat emitter may take the available energy and radiate it for efficiently then a light of the same wattage but its all still EM energy). Ok I admit it...I just don't know