Reflector Question

[colin779]

The reflectors on my aquarium look like the reef optix (that style). The question I have is due to space in my canopy. Will it have any adverse affects if I bend (close the spread) on them. Will this just direct more light down over a smaller area? Or will it actually reduce the amount t of light reflected down? Thanks!

 

[Krish]

I guess it all depends on the tank. A reflector does nothing more that reflect light so as you suggested, bending it will change the spread, but may not be bad enough to where it causes an issue. Like I said, it all depends on the tank. Imagine a 4 foot tank with two reflectors that barely make full coverage and you bending the ends. Chances are the light from both reflectors may never intercept one another at the center so you end up with a dead spot. Consequently you bend them, but push the reflectors closer together and you get great coverage throughout the tank, but the outer edges suffer. on a smaller tank you may not have an issue at all. Definitely though it will change the light spread, but it's hard to say to what extent without actually seeing what tank it is on, how much you bend it and even how high the light is placed. The higher you go, the wider the spread at the bottom, but the less penetration you get into the tank lol. Seems like too many variable :lol:. If it's the only way for it to fit then bends them as it is your only option and play with the positioning to where you get best coverage. You never know, there may not be any negative impacts on your tank. If so, just put the lower light demanding corals in the lower lit areas.


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[colin779]

Sound like im just going to test it out =) The tank is a 90, coverage hasn't been an issue before, I've just noticed I had a lot of light that seemed to be hitting the wall above the top if the tank behind it, and also the floor in front of the tank. Ill see if I can see a difference when the lights come on today. I need to take a picture anyways because I finally finished pulling all the sand out and re aquascaping. I think it looks pretty awesome now and much more natural. Picture will be on the thread I started about going bare bottom.

 

[colin779]

Experiment over, reflectors bent closed is dimmer then left as they came from factory. Seems like the reflector was reflecting more light back at the lamp then down.

 

[dnjan]

Yes, reflector shape is very important. With a decent reflector, more light will enter the water after hitting the reflector than directly from the bulb.

The reason is that as the angle between the light beam and the water surface decreases, more light is reflected off of the water surface (meaning that less light penetrates).
A good reflector will send light close to straight down for maximum penetration and minimum reflection.

 

[colin779]

Nice, did not know that, good information! I wasn't aware that the angle of the reflective surface had that much to do with it.

 

[Krish]

Nice, did not know that, good information! I wasn't aware that the angle of the reflective surface had that much to do with it.

Oh...Definatly! Take a look at my reflectors in the picture below. Some people use to run this type of reflector with the reflector layed out parallel to the front and back of the tank (so long ways side ways). The proper way is how I have them mounted which is perpendicular to the front and back of the tank which allows the light to spread across the whole tank.





So this is what happens with the reflectors setup like that in the sketch below. As you can see light spreads out to the sides and intercepts one another so no dark spots in the middle. You spin those reflectors sideways and you end up with the light spreading from the front to the back of the tank with a dead spot in the center where no light spreads to so as Don mentioned, reflectors play a major role. They do all of the work.

 

[BigAl07]

Believe it or not there is a lot of science and R&D that goes into good reflectors. As stated already the angle the light strikes the water is of utmost importance because even a slight deviation can have drastic effects. The reflector directs light in the most efficient way from the portion of the bulb not facing the water and manipulates it until the most rays possible are striking the water at an optimal angle.

Good reflectors make a WORD of different and bad reflectors can be worse than no reflectors.

 

[colin779]

I wanted to mount my reflectors that direction but they would not fit in the canopy that direction with my actinics. Also the fans are mounted to the sides of my canopy and blow across so i think the air from the fan would just run into the side the the reflectors. Maybe that's a project for me this weekend to see if i can get them to fit in that direction. It makes more sense for them to be oriented like that.

Do you think i am going to lose much cooling if the air hits the side of the reflector instead of flowing through them? The back of the canopy is open so it will still go out at the same rate, just not the same way.

 

[Krish]

Once air can escape you should be fine. I had 5 fans in my canopy. 3 sucking hot air out of the top and two blowing cool air across the water's surface. The main thing is not to let the fans blow directly on the bulbs. If you want some pics of how I had the fans setup I can post them tonight when I get home and to my pc. Might spark a few ideas


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[dnjan]

To expand upon that a bit - What Krish has shown is basically the light that comes directly from the bulbs (his pink lines).
In addition, there is light from the reflector, coming almost straight down. That would mostly just cover the area under the reflectors.
Between the reflectors, the area covered by Krish's crossing pink lines, the light from just one of the bulbs is not that good, since a lot of it is reflected off the surface. But with both bulbs contributing to that region, the intensity is much better.

As a side note - the allighment of these reflectors (parallel or perpendicular) is more important for longer tanks (60" or so for two-bulb setups). If your tank is only 48" long, the difference between parallel and perpendicular reflectors is not so critical.

 

[colin779]

Very interesting, so on my 90 would it be worth changing it over?

Since I've re aquascaped this past weekend after pulling all my sand out the tank looks like this:

I have noticed the right side has a little bit of a dark area, but i think its due to the tonga branch with the green star polyps hanging out over the stuff below it (hard to see in picture but its pointing out from just below and to the left of the candycanes). Not sure if it would help me out, what do you guys think?

 

[dnjan]

What are the tank dimensions? And reflector type?

 

[colin779]

The tank is a standard 90, 48x18x24. The reflectors are a Sunlight Supply Reef Optix 2. I got them from my lfs but the have them on reefgeek. I think they are pretty basic but seem to do a good job. They are a dimpled aluminum. The halides are only 175w so there's only so much a reflector can do =)

 

[Krish]

What Don posted is correct and applies to your tank as it is a 4ft tank just like my 75gal was. I however ran dual 250w metal halides for a bit more punch. The pink arrows I showed were simply put there to show the spread and not necessarily where all of the light will shine. I should have stated that, but was stuck on making the point of the light spread out to the sides.

In any event, here is how I set up my fans to give you some ideas just incase it is useful.


the red arrows point to all of my fans. The 3 on the top sucked hot air out through some vents and the two mounted on the sides sucked in cool air from outside and blew it across the surface of the tank






Here's a shot of the vents






And why not the light from the halides

 

[colin779]

Nice, great pictures! Me and my inability to wait once i want to do something is about to pull the canopy off the tank and rotate my lights. I don't even have the actinics plugged in since i switched over to the 20k's, so I'm just going to eliminate the fixtures from the canopy. I'll take a couple pictures along the way =) Hopefully wont take more then a hour to finish off.

 

[colin779]

Do I want to line the lamps up slightly more towards the center of the tank in each hole, or do I want them right in the middle of each hole??

 

[colin779]

I went with slightly more towards the center of the tank. Seems to be ok so far =)

 

[Krish]

Cool man...Missed replying to your question. Center should be good. Post some pics when you get a chance.


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[dnjan]

And why not the light from the halides

Hey Krish - do you watch people do welding as well???