Lighting Sense?

Philosophos

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Wouldn't it make more sense in terms of giving viable light to lower foliage to angle a light more like this:

angledlight.jpg


This would be used in conjunction with other lights in a normal configuration. Seems to make more sense to me than just blaring light down from up top; it creates a better angle, which is along the same principles of better lighting spread.

-Philosophos
 

dutchy

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And some of the plants would grow to the front, to the light that's nearest, in a kind of 45 degree angle.
In this configuration one window is totally shielded, while the other one is completely illuminated.
When directed straight down, both windows reflect some of the light inwards.

In summer I get a lot of daylight into my tank. In only 2 hours, some plants angle at 45 degrees to catch the light. They start to go straight again when the lights of the tank switch on.

So not a very viable option in my opinion.
 

Philosophos

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This would be a design to be used in conjunction with other lights shining straight down. The idea would be to offer more PAR from directly above, but also have it available from the sides enough to satisfy minimum PAR.

The inside glass does reflect, but obviously the lower back of any tank with tall stems would be benefiting from this the least. This is the area I'm trying to target.

-Philosophos
 

dutchy

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ok...I see. That could work I guess. Well, it should be easy to measure the improvement with a PAR meter. The 45 to 60 degree angle to the leaves will be less effective though but more light should reach the lowest leaves anyway, We would have to measure the difference with the PAR sensor directed straight up.

Would be nice if the group buy came through. I'm planning a new tank so I want one.
 

Philosophos

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I completely agree about the PAR meter group buy. I'm going to be trying to get local interest if I can, though it's doubtful.

I've got a tank with a hood on it that's just perfect for this concept, though it's in dry start mode right now. Once it's filled and there are some stems around, I want to give this a try.

-Philosophos
 

Biollante

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Tricky Darn Plants

Hi Philosophos, Dutchy,

Dutchy is correct, I have this situation with a number of tanks. Even with substantial overhead lighting, plants are pretty darn tricky and they do turn and grow quickly to take advantage of the light.

Additionally you have to contend with angle of incidence and refractive index differences along the water air boundary.

I am also sure Dutchy did not mean to slight the prominent Dutch mathematician Christiaan Huygens, of the Huygens–Fresnel principle so we deal not just with reflection and refraction, but diffraction as well. :rolleyes:

If you have a university library nearby you may wish to access Principles of physics: a calculus-based text by Raymond A. Serway, John W. Jewett, if you have the math background or Physics for scientists and engineers, Volume 1 by Paul Allen Tipler, Gene Mosca. The Encyclopedia of surface and colloid science, Volume 3, by Arthur T. Hubbard

Anyway, I agree on the PAR meter I just got mine, so far the surprising thing is the par values are higher in the areas I have checked than I would had guessed. I felt bad about dropping out of the group buy…

Biollante
 

Philosophos

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Thanks for the references. I'll definitely be reading up on all the concepts you've mentioned when I get the PAR meter. For this experiment though, one PAR meter and $2 worth of materials will be all I need to test and compare actual results. The nice thing is that this tank is already over lit, so much of the loss from reflection off the surface won't be a big deal; even 1/4 of the light will do for my purposes.

Should the stems alter their growth to bend towards the light despite higher PAR values from above, I may start playing with spot lighting to alter growth direction to get certain effects.

-Philosophos
 

Biollante

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Hi Philosophos,

I saw a display tank a few months ago that had lighting underwater back a little more than half down.

It had an oddly interesting look, I don't have any idea the efficacy or how much effort to keep it clean and clear.

I have wondered about spotlights for plants that need higher lighting. Now days with the T-5 lighting, efficient reflectors with tubes spread further apart it would seem to offer an opportunity to intersperse spotlights.

Many years ago I used spotlights as accents and/or to highlight artifacts, in addition to general lighting affects in non-plant tanks during my 'art' phase.

Oh well.

Biollante
 

Tom Barr

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This is only a one parameter (direction) light design, what would occur if you had another going the other way on the rear?
Then one in the middle?

Which of the possible say.........7 different combinations might work best for plants?
For viewing fish, our own eyes and perceptions?

For plants, all 3.
For our eyes, the suggestion above.
For reduced glass algae and still decent growth, likely the one directly in the middle, and the front angled one.

For spread with min wattage, the one in the front and the one in the rear.

Depends on the goal/trade offs.

With my open top, I can tilt the fixture to do this, vary the no# of bulbs/color temps etc, to get pretty much most of these effects.

I cannot get a full bowl effect however.
Maybe a flexible expandable hood would be nice?

I use the above angling for fish coloring highlights for Discus tanks.
The light tends to be lower powered and color aesthetic specific.
This gives the fish their best appearance.

1= bulb, f= front, m=middle and r=rear

1f
1m
1r
1f:1m
1f:1r
1m:1r
1f:1m:1r

These are the various comos for 3 bubs and their positioning.
You can angle these towards the center of the tank(or adjust them individually).

It's nice to be able to adjust each set up to suit your goal with the plants/aquascape.

You quickly see how spread and directional usage, algae on glass etc make this a complex issue.

Seldom discussed........

Regards,
Tom barr
 

essabee

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Big roomy tops with reflective surface and multiple light bulbs appears to be the best bet for getting the lights right for the planted aquarium. This will cause the light from the bulbs to be reflected from all directions on to the surface of the tank. Shadows will be minimised to only a small umbra under the leaves. If the top does not allow any light to escape the efficiency of the bulbs will not be diminished beyond the albedo of the reflective surface.
 

Philosophos

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Well Tom, unfortunately this is a 2 light situation for me. I should've gone with 3x28w instead of 2x54w, but the programmed start ballast was too tempting. Besides, it was the sunblaze single strips by the people who do Tek lighting with geissman bulbs or Current with ribbed splash guards.

Still, it's good to now that this is a technique that's been used with success. I didn't even think about how it would play off the fish. I guess I've got something new to play around with in a month or two once the dry start phase is done :D

Essabee, thanks for the reply. Some of the principles you are mentioning are what I've tried to keep in mind for the tank I'm working on. Your post is making me consider adding some extra reflective material inside the canopy, besides the individual reflectors, to increase efficiency.

-Philosophos