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Troy,

I'd be interested to see Jerel's results. The potential exists that while he may experience increased coral growth (skeletogenesis), he may also experience color changes in his corals. As of yet (at least to the best of my knowledge), the debate regarding what causes color changes in corals has not been resolved. I know that Richard Harker has commented that his ability to use natural sunlight on his new reef set up has caused many of his darker colored corals to move from brown shades to more tan shades, and that the other pigments (blues, pinks, etc.) have intensified. So while corals may in fact have to expend energy to protect themselves from prolonged exposure to high energy light waves, that same protection may be what causes the corals to manifest the colors that we desire . . . might be a slippery slope where we have to choose which of the two evils we prefer.

Hi,

<blockquote>quote:<hr> Won't happen.. Have you ever had the surface of your tank perfectly calm ALL the time? I haven't, Not with proper circulation in your tank you won't. Those "glitter" bands you see will move. Show me a tank where they don't move and I will show you a tank with not enough circulation.

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Glittering only shifts the light by a limited amount. There will always be a case where a specific area in your tank is not as well lit as others.

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Quote:

Why? Blow it at the waters surface and you will get the best cooling results through evaporation. Those running MH's or any high heat lighting in your hood will find this out. The amount of cooling you will get through cooling the reflector is so minimal in comparison to what you get from evaporation it is a waste of time and energy IMO IME. I have tried it. I am running the fans to blow across the H2O and will in any future systems. I recommend it to anyone running MH or experiencing heat problems in a tank.

Well...that wasn't quite what I was getting at....I was talking about the fact that shiny reflects warm up tank water faster than white reflectors. The heat that isn't transfer to the water is stored on the painted reflector -- which can be removed by fans (think of it as a heatshink).

<blockquote>quote:<hr>I can't understand the point of diffusing something that is supposed to provide point source lighting???? Agree 100% here.

If you want to diffuse your lighting and then compensate with more bulbs or lamps go for it. Most here are trying to save money where they can by DIY'ing the ballasts etc. You are shooting yourself in the foot by reducing what those lights put out with diffusing IMO.

<hr></blockquote>

Reflector design is still more important than diffuse vs specular. A well design diffuse reflector would outperform a poorly design specular reflector -- regardless if it is a line source, point source and a diffused source.

- Victor.

[ 14 February 2002: Message edited by: reefburnaby ]

Andrew, I hear you. If light intensity does turn out to be the primary cause of the "brighter" pigmentation then I don't think there'd be any decision to make. I'd give up a little growth for the nicer colours. The context of the information I was "quoting" [img]images/smiles/icon_wink.gif[/img] from was more for achieving maximum growth at the best returns (least energy). Really I've added nothing useful to the conversation. Just added a poorly conceived point about the differences between nature and the captive system. Must shut-up now.

Hi,

I would agree that focusing light for corals is a good thing -- that is if the corals want more light. However, if your precious SPS coral sits between a bright band and a no/low light band (assuming no glittering), then half of you SPS is not doing well...and the other is doing very well. In other words, there is a chance that half the SPS will actually starve. I know this is an extreme example and it rarely happens because....

Did you know that the spider reflector actually spreads the light out rather than focusing it ? If you do a ray trace, you'll understand what I am talking about.

BTW, diffuse lighting doesn't suffer from the depth effects as much as spot/specular light -- its a waveguide phenomenon with respect to the water and the glass walls (okay...that's getting really technical...). So...its a bit more tricker than one would think.

As for the cooling thing...we could try blowing at the the reflector from side, but not at the bulb. If there is a will...there is a way [img]images/smiles/icon_smile.gif[/img] Besides...its the intensity that counts ? right ?

- Victor.

[ 14 February 2002: Message edited by: reefburnaby ]

<blockquote>quote

Quote:

Glittering only shifts the light by a limited amount. There will always be a case where a specific area in your tank is not as well lit as others.

The glitter lines in my tank shift quite a lot. It is noticeable enough that it is almost hypnotic. With proper circulation and movement of the water in your tank you get a fair bit of light movement throughout the area of the tank being covered by the MH. The gliter lines don't sit still that is for sure. The surface water in my tank is very convoluted and moving constantly. Which also moves the lines of intensity constantly.

And of course there is areas that aren't as well lit as others. If you want the same coverage throughtout put multiple lights and/or a reflector to focus the light. This will also be dependant upon the shape of your tank.

<blockquote>quote

Quote:

The heat that isn't transfer to the water is stored on the painted reflector -- which can be removed by fans (think of it as a heatshink).

It is a heat sink. But removing that heat from it isn't nearly as efficient as putting a fan that is hitting the waters surface. I have tried. And had planned on doing this on my next tank until I found the best way to remove heat was not to hit the reflector with a fan but blow air across the water.

As an aside unless you had the fan directly(within a few cm's) of the reflector it, like water out of a pump, loses velocity which will aid in cooling. Once you get any distance away from the reflector the speed at which the air is passing over the reflector and pulling away the heat stored is minimal. IMO. On my 45 with a 24"x24" hood I may get some benefits from this. On anything larger I don't see it benefitting heat removal. Even with my smaller hood, I will still go with the fan on the water. If it works better(more efficiently) why not use it?

<blockquote>quote

Quote:

Reflector design is still more important than diffuse vs specular. A well design diffuse reflector would outperform a poorly design specular reflector -- regardless if it is a line source, point source and a diffused source.

I know that but my point with the statement

<blockquote>quote

Quote:

If you want to diffuse your lighting and then compensate with more bulbs or lamps go for it.

was if you are specifically buying point source lighting to get the intensity that corals need and thrive on, why would someone want to diffuse it?????? If you are going to waste the money like that send it my way. [img]images/smiles/icon_rolleyes.gif[/img]

All you need to do is look at this graph.

http://www.animalnetwork.com/fish2/a...1101/f11sm.jpg

Look at how reflective white paint or flashing is. Then look at aluminum. I can't imagine how much light I am losing as I HAD to go with white paint. I can't wait to throw that reflector sitting in my new tank on and measure the lumens again. Nuff said.

Anyone still want to diffuse point source lighting? Send me the cash you were gonna spend on MH and I'll send you some NO ballasts. Equal trade IMO. [img]images/smiles/icon_rolleyes.gif[/img]

[ 15 February 2002: Message edited by: DJ88 ]

Darren, don't take this wrong but I think you need to reed the definitions of Specular reflectivity, and Diffuse reflectivity. from what you are posting it sounds like you think Diffuse reflectivity doesent reflect at all. this is just wrong.. actualy here is the definitions for all to see Oh there is also Spread reflectivity which is kinda a mixture of both..

"Specular reflectivity is the type that occurs in a mirror or any other highly polished surface. In the case of specular reflectivity, the angle of the reflection is equal to the angle of incidence. When we look into a mirror, the objects we see are at the same angle to the mirror as the angle at which we are looking at the mirror. Spread reflectivity is similar to specular reflectivity, but the reflected light is more scattered about the reflected angle. Diffuse reflectivity, as the name implies, is reflectivity where the reflected light is spread in all directions. An example of a diffuse reflector is a white painted reflector."

now havign said that... which one is better.. it totaly depends on what you are doing.. if you are rich and can afford lots of MH bulbs then go for the "Specular reflectivity" ie. spectral alumium (which is what I am using for my floresents) but if you can only aford say 1 MH for a 3 foot tank or 2 for a 5 foot tank you might be better going with a "Diffuse reflectivity" type reflector like hammer tone or good forbid white painted flashing. [img]images/smiles/icon_smile.gif[/img] the idea is to spread the light over more of the tankto get a even lighting and make due with what you have. I have seen tanks that are realy bright in one area and dim in another becuse they coulden't aford enuf lights and quite franky it looked bad IMHO.

I know you have enuf lights that you don't have to worry about this and by the sounds of it most estableished reef people on this board do also.. (Andrew when are you going to host a meating so we can get a chance to see your tank?) but for people who are putting togeather new systems and want to spend more money one substrates and skimmers and such, or are not planning on keeping SPS for a while a "Diffuse reflectivity" type reflector might be the best bet, keep in mind I do not avocate the painting of the inside of your hood to make a reflector becaus it is just plain flat and won't work as good as if you bent up a piece of white flashing.

to see what I mean take a small piece of "shiny white flasshing, and a miror. go to a dark room and shine a focused been of light into the miror so it reflects onto the wall.. then do the same with the flashing.. the circle from the flashing will be a lot bigger than the one made by the miror, yes it will be less intense but it will give a larger area the same amount of even light. enuf said about that.

Also I think victors idea of blowing the back (or side) of the reflector instead of the water surface would be good if you wanted to cut down on the evaporation rate.. the more air yyou have blowing at the surface the more evaporation you have. So by cooling the reflector you will drop hood temps which will also help to lower your tank temps.

Steve

<blockquote>quote:<hr>to see what I mean take a small piece of "shiny white flasshing, and a miror. go to a dark room and shine a focused been of light into the miror so it reflects onto the wall.. then do the same with the flashing.. the circle from the flashing will be a lot bigger than the one made by the miror, yes it will be less intense but it will give a larger area the same amount of even light. enuf said about that.
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Wheew....took a while but I finally made sense of that.

Ok Steve, now that you've admitted that the intensity would be diminished with a diffuse reflector, ask yourself this: "Is my goal to be able to keep mushrooms alive in every square inch of my tank, or is it to be able to have sufficient intensity to keep SPS alive and thriving?" Per unit area, a specular reflector will provide more available light.

Sorry, can't have a meeting to see my tank; I don't have one at the moment (I think you might have been one of the few people who didn't know this. I answered lots of questions about this at the last meeting at Victor's). I sold my tank to Darren in the summer so that I'd be able to focus on my edumucation and not have to choose between neglecting my tank and excelling at school (don't want to have to be a stoker). However, I'm sure you knew this before you suggested I have a meeting so you could see my tank. You were apparently trying to be a "smart ass" but it went right over my head, as I'm accustomed to your stupidity.

When the temp goes up to 25 degrees Celsius in the summer try blowing (un air-conditioned) air at your reflector to cool the water temp as opposed to using evaporative cooling...let me know which one works more efficiently for keeping the water temperature down.

Ahhh their is the Anderew we all know and love..
I wasn't trying to be smart.. I am a stoker and acording to you there is no way I could be smart, and I was serious when I said I would have loved to see your tank, and yes I was probable one of the few that didn't know that you didn't have one.

Steve

Steve, if you honestly weren't trying to make a backhanded comment, then I apologize publicly for being a jerk; I was out of line with what I said. I think I'm more irritable that usual (guys like Troy who've seen my normal behavior over the years know that I'm "ornery" but not usually this bad) being that it's midterm time right now and I'm stressed out. Maybe I vent that stress and frustration here, and I really shouldn't do that. Here's what I'll do: I'll take a break from the board until my midterms are finished and see if I'm less of a jerk when things have calmed down.

Once again, I apologize to everyone on the board for my poor behavior, and especially to Steve.

Hi,

<blockquote>quote:<hr> It is a heat sink. But removing that heat from it isn't nearly as efficient as putting a fan that is hitting the waters surface. I have tried. And had planned on doing this on my next tank until I found the best way to remove heat was not to hit the reflector with a fan but blow air across the water.

<hr></blockquote>

Well...couldn't you put it on both ? Both water and reflector ? [img]images/smiles/icon_smile.gif[/img] I don't have HIDs, but I have heard that blow air at both water and lamps helps reduce the water from heating up too much. Just a suggueston...

As for the diffuse vs specular, I guess we'll need your light meter to settle this. You measure 20,000 lux....how far away from the lights was this ?

- Victor.