# Pendant lighting vs "traditional" lighting



## jeffkrol (Jun 5, 2013)

lovingHDTV said:


> I've looked about and didn't find anything on this topic. So I thought I'd ask.
> 
> What are the pro's con's of pendant lights vs the more traditional "linear" lights?
> 
> ...


generally speaking strip lights are more uniform. your pend. are 2 light cones that intersect.
most tanks are not square which is really what "a" pendant shines at..

Secondly less light spill.. since the fixture is tight to the top
3rd is lower power needed for higher PAR. light does not "drop off" as it would in a pendant..

that said you can have a "pendant bar" light w/ the proper optics and intensity..

To give you a better idea of light falloff, the inverse square rule..
At 2x the distance light intensity decreases by 4...
Just an example of 2 "pucks"..


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## Kathyy (Feb 22, 2010)

10 months ago I bought a single 5' long LED fixture to replace 2x1' wide metal halide pendants lighting my 6x2x2" tank. I'd been using MH pendants since 2000. While 2 MH were fine to cover the 67" of tank that needed to be lit there was a whole lot of light spill as it was hung 16" over the tank. Didn't need any other light on in the room at night! The LED is hung the same 16" up and there is less light spill and now we do turn lights on in the room at night. I did like the flexibility of the small fixtures, 2 were fine for 5', bought another for the 8' then back to 2 for the 6' tank. It is a pain to level the fixtures and hide the cords. You need to find more room for the ballasts and wall sockets as well. 

I have a wide tank, a single fixture isn't going to light the top unless it is suspended. I much prefer the look of suspended lighting, it is out of the way when working on the tank and much less likely to get wet or get dunked. I don't know about other LED fixtures but mine puts red and blue spots on the ferns above the tank. My floating pennywort 16" below looks normal, I wouldn't want it to have red and blue spots.


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## lovingHDTV (Oct 15, 2008)

That makes sense. I knew the pictures help.

I've priced two systems out and they seem to be about the same $$$ wise. Lots to think about, but I think you have me leaning towards the more traditional approach.

thanks,
david


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## jeffkrol (Jun 5, 2013)

lovingHDTV said:


> That makes sense. I knew the pictures help.
> 
> I've priced two systems out and they seem to be about the same $$$ wise. Lots to think about, but I think you have me leaning towards the more traditional approach.
> 
> ...


W/ the right light you can still hang a linear fixture..
Beam Angle Selection Guide

45 degree optics would be pretty comfortable at 2 feet above the water line.. Would cover 18" front to back approx..

30 degrees 3' above the water.. same 18" approx...

A pendant that has lens choices as well:
https://orphek.com/atlantik-p-planted-aquarium/


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## lovingHDTV (Oct 15, 2008)

I was looking at the 12w Luxeon LEDs from Steve's LEDs. Thinking of putting 8 of them across the 36" tank. That would put each one about 4.5" apart, provide plenty of light. They come with a beam angle of 90 degrees so that should work for 12" above the water. That let's me see in the top.

maybe a good compromise. With he has the higher CRI version. He only carries the 70s.

david


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## jeffkrol (Jun 5, 2013)

lovingHDTV said:


> I was looking at the 12w Luxeon LEDs from Steve's LEDs. Thinking of putting 8 of them across the 36" tank. That would put each one about 4.5" apart, provide plenty of light. They come with a beam angle of 90 degrees so that should work for 12" above the water. That let's me see in the top.
> 
> maybe a good compromise. With he has the higher CRI version. He only carries the 70s.
> 
> david


yes those are sweet LED's.. 
A question, did you pick a K?
Also I don't recommend Steves drivers. The driver chip topology is a bit old school.


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## lovingHDTV (Oct 15, 2008)

The K is what I'm looking at now. I like the BML lights, but don't like the 0-10V. Makes it a bit harder to PWM.

My 96w PC bulbs are 6500K, and I like them just fine, but really don't know. This is where I'm stuck by analysis paralysis 

So I'm looking for something in that ball park. One thing I can't understand is when a light has only a single Cyan led. How does that effect the entire tank. There is no way that can happen. So they all show these plots as if all the LED contribute the same uniformly across the tank. That can't happen.

david


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## jeffkrol (Jun 5, 2013)

lovingHDTV said:


> The K is what I'm looking at now. I like the BML lights, but don't like the 0-10V. Makes it a bit harder to PWM.
> 
> My 96w PC bulbs are 6500K, and I like them just fine, but really don't know. This is where I'm stuck by analysis paralysis
> 
> ...


6500K PC and 6500k LED are not really equivalent..

Yea those one cyan (per 12" board ) is kind of head scratching but there is an advantage. Cyan is quite visible to the human eye. Over my 40b I run 4 cyans and since it is a single channel I can see the difference between zero and 4 at full. It is visible. top has cyan at 90%












.


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## klibs (May 1, 2014)

I personally don't think I would go pendant unless I had a square tank. Then I'd just get a kessil all day.


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## lovingHDTV (Oct 15, 2008)

That is disappointing to see that LED 6500k is not PC 6500k. Is there some way to judge the color?

I'm thinking something like this for a 12" segment:
Custom LED Report

I'd put each color on its own controller. Then I could have a bit of control over the color. My biggest concern is buying all the lights and not liking the color.

Anyone else have ideas on a nice color? I think the plants will be fine, it is just if I like the colors. A couple other variant:
A little warmer;
Custom LED Report

A little cooler:
Custom LED Report

david


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## jeffkrol (Jun 5, 2013)

lovingHDTV said:


> That is disappointing to see that LED 6500k is not PC 6500k. Is there some way to judge the color?
> 
> I'm thinking something like this for a 12" segment:
> Custom LED Report
> ...


Well don't get me wrong it is just 6500k is a CCT and as an average a whole host of spectral differences can add to an overall color temp.

Most people will "see" a bluish tone w/ LED that may or may not be present w/ CFL's or any other 6500k light source..

going s bit back to LED's and myown "opinions" the main problem w/ LED "look" is 1)lack of cyan and 2)overabundance of blue and when compensated for an overabundance of "yellow"

As such I do lean to 4000K for the warm but not warm tone.. supplemented w/ cyan..

IF you go DIY one of absolute best design (arguable of course) is a R,G,B,WW,CW array. This allows ANY tone/shade/highlight you wish to have..

going to next best would be R,G,B,W.

since changing the blue content will cool the light your base white K can be increased or decreased by turning on the blue or red channel..
the green is more for you..

Look to on line tank pictures
Finnex RayII is 7000k
Beamsworks are mostly 6500k for fw 10000k (w/ actinic) for saltwater,,

The Fluval freshwater performance series has a CCT of 5200K
Aqualife & Plant Performance LED | Aquarium Lighting | Fluval

Look at any Amazonia style tanks for lighting that looks 3000-ish K.

NOTE: don't use green.. it is a bit pointless since most white LED's are green rich.. Use cyan
You want to fill the dip a bit:









Falling down the rabbit hole:
http://forum.buildmyled.com/index.php?threads/sunlight-analog.277/


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## lovingHDTV (Oct 15, 2008)

Good thoughts.

Maybe it is just best to get three different boards.

1. Cool white (6500), Warm White (4000), Blue (470)
2. Cool white (6500), Warm White (4000), Cyan (505)
3. Cool White (6500), Warm White (4000), Red (625)

run 5 channels, and set to what "looks" best.

This looks to give good results, and give you the ability to "tune" the light color with the controller.

david


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## jeffkrol (Jun 5, 2013)

lovingHDTV said:


> Good thoughts.
> 
> Maybe it is just best to get three different boards.
> 
> ...


Somewhere BML has a "custom" board @5000K
You may like that one as well
nothing but 6500k and 660nm red
New 5000K Planted Tank Spectrum | Build My LED - Lighting Discussion Forum









adding "a" cyan might be interesting.. 
You may want to think about a 
DIY again using this controller, Meanwell LDD drivers , ps and diodes


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## lovingHDTV (Oct 15, 2008)

I'm in the process of building MrMann variation of the iAquaTouch. It has 6 pwm LED channels.

Taking your advice on Cyan over Green, I came up with:

Custom LED Report

I put the extra cool whites on the end to get the report and not "really" change the light. Adding the 1x blue, 1x red, 2x cyan really showed an improvement. I would run all the different colors on separate channels.

Wow these start getting expensive 

david


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## micheljq (Oct 24, 2012)

Ultimately i want pendant lights, nothing on the tank, so much easier when doing water changes, trimming, cleaning, etc.

If a light is too powerfull, it can be set higher if pendant.

The only thing right now which does not let me go with pendant lights, is my wife.

Michel.


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## MrMan (Dec 5, 2014)

Lights are my next project and i'm in the same boat as you right now. I've decided to go with the rapid LED premium heatsinks. My tank is 36x18x18 so i'm thinking either :

2 x 12" heatsinks, each one with ~12 XP-G white LEDs plus some color LEDs, each heatsink over half the tank
-OR-
1 x 20" heatsink, 2 Vero 18 5600k COBs, each one would be lighting a 18" cube basically

The Vero system will be cheaper and I can always add some extra LEDs around them for color or effects. I'd like to have the lights hanging a bit either way. Just worried two Vero18s won't be enough and then the heatsink would be too small to add more.


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## Hoppy (Dec 24, 2005)

What is the definition of a "pendant" light? It could be any light that is suspended well above the top of the tank. That light could be square, round, or rectangular.

I think the goals are:
Get the right amount of light at the substrate level in the tank.
Get that amount of light over as much of the substrate as you can.
Get that amount of light over as much of the tank, top to bottom, as you can.
Avoid light spillover and resulting glare.

Those goals are easiest to accomplish using a light suspended well above the top of the tank. But, that increases the risk of spillover, so much more effort is needed to avoid that spillover.


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## lovingHDTV (Oct 15, 2008)

I guess I was thinking a pendant light has a single main source of light. That could be a single LED, COB, spotlight whatever. Traditional would be a the main source of light is distributed across the light fixture.

david


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## Hoppy (Dec 24, 2005)

It isn't easy to get even close to uniform lighting with a near point source light, like a LED, or a small MH bulb. If you go that route you will probably find it much easier if you use 2 or 3 lights, each hanging over the tank. One possibility is using CFL bulbs in small dome-like reflectors. Many people have done that successfully.


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