Steven A. Ellis
Kennesaw, GA
>
>First off, let me address that I think for natives, this is only a good
>solution for larger, taller aquaria (which is what Brian was asking
>about). I wouldn't go putting a 250 watt halide on a 15 gallon... ;)
>With that said, lets discuss heat a little bit...
>
>The "Heat of Halides", to me, is somewhat of a myth.. I think it's
>perpetuated by a couple of things and I'll address each indiviually:
>
>1) The Raw wattage of the lamp.
>2) The wattage per surface area of the lamp.
>3) The misunderstanding that the extra UV and IR the halide lamps put
>off is "heat".
>
>The first thing to understand about lighting, with regards to heat is...
>"A watt is a watt is a watt." It doesn't matter if it's a standard
>flourescent, a pc, halide, an energy saver, high pressure sodium, etc.
>It's still a watt, it still has it's own unit of heat associated with
>it.
>
>If you were to put a comparable number of flourescent watts and halide
>watts in a heat monitoring device, you'd see the same change in
>temperature from both. It's the same heat output. However, this is
>where Halide gets it's bad name.... In this experiment, for 175 watts,
>you had 6 inches of glass envelope on the halide... And you had over
>200 inches of nomal output flourescents to achieve the same wattage!
>Extrapolate that out to a 400 watt comparison :)
>
>As you can see, the heat generated is dispersed over a greater surface
>area in flourescents and they don't seem so "hot", which is a certain
>misgiving.
>
>True "Heat" is easy to dispell. If you have an open top tank, you can
>just set a regular oscillating fan right on it. A friend of mine put
>one of those cheap clip-on fans you can get at Walmat. Evaporation can
>dump the temp in an amazing fashion. As well, if you had the halides on
>pendants, none of the heat transfer would go to the tank (unless you had
>warmed the room).
>
>I'm stubborn and a purist about halide lighting... I still use enclosed
>canopies. I use 4" computer Fans to vent my hoods. However, in my
>wanning youth, I'm finding myself to be less of a zealot about it (but
>maybe that's a general trend ;). When it heated up last week so early,
>I wasn't ready to deal with it, but considering that this is 1500 watts
>of ligting over 72x18, I don't think it was any reason to throw the
>book out on halide, nor do I think *that* lighting configuration is
>anything you would want for native aquaria. I will note tho, I didn't
>really have to fuss much with the 175w tanks, and I didn't even have
>fans on them (which is getting corrected this weekend ;)
>
>So that's pretty much a quick triste on heat.
>
>Now for the fun... The UV and IR. I think this is the single greatest
>perpetuator that halide is somehow hotter than flourescents. You stick
>your hand underneath a halide lamp, it feels hot right? Is that heat?
>
>I did a demonstration one time at a friends of ours shop. She has a
>greenhouse and uses halide to suppliment the SPS coral and tridacnid
>clams which are all photosynthetic critters. We had the good fortune
>to have the halides on a pulley system, and big big fan to do the
>demonstration.
>
>"Put your hand under the light, is it "hot"?"
>"Yes."
>"Put your hand down by the water under the light, can you still feel the
>heat?" (this is about 2.5' from the halide)
>"Yes I can still feel it pretty intensely, but it's not as hot."
>(turn the fan on.. wind tunnel ensues)
>"Put your hand back under the light, is it "hot"?
>"Um. Yeah. A little less, but it's still definately hot."
>"Put your hand back down by the water. How comperable is that the first
>time?"
><everyone 'whoaaaaaa'>
>"The same as before!"
>
>I always love seeing shocked faces that look up like "NUHT UH!!!" ;)
>
>It's this extra energy that comes from the halide lighting that endears
>it to those of us who use it to rear photosynthetic organisms. In
>arguing the case of those critters I say "They've made a living off the
>sun... Why wouldn't I give it to them?" :)
>
>With that I'll digress a bit and rethink native. I'm not sure if any of
>this really plays into your aquaria, if you're using lights to just
>make a nice brite aquarium, or if you're interested in rasing plants,
>etc but I have some time while doing an import here so I thought I'd
>write a bit about it :) I don't think a well planned system you would
>have any heat issues. In fact, for anticipating for the heat, I seen a
>lot of aquarists drop their tank temps because they got the floro heated
>glass off the top, aquired a real gas exchange, began utilizing
>evaporation and etc etc. It may actually be intuitive.
>
>Now there's more that would have to go into just putting new lights on
>the tank... There are issues of nutrient conversion that would *have*
>to be addressed. You've just given so many new players (algaes) the
>ability to step up to the plate, but don't let that scare you. It's
>really not all that bad to deal with, and the rewards reciprocate :)
>
>If you'd like to discuss more, poke around the web a bit and see what
>others have to say about lighting. It will probably get overwhelming,
>mainly because a lot of people are trying to sell you something and they
>don't understand it to begin with. But as you have questions, you can
>post them here and I'll try to answer best I can (I'm sure there's other
>who have experience with all this too).
>
>I'll warn you I'm not into the physics side of things, so if we start
>getting into Light Theory, I'm going to step away. I like natural
>history, and more so, I like watching natural history work. So at times
>in those situations (I'll just confess now) I have a tendency to grab my
>"Anecdote Ray Gun" and say "Okay Theory Man. Let's see you grow it!"
>;)
>
>Todd
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