DIY Pendant LED unit - The Planted Tank Forum
 
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post #1 of 11 (permalink) Old 08-28-2017, 11:12 AM Thread Starter
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DIY Pendant LED unit

I am thinking of setting up a new planted Nano, it'll be a 5G tank with DIY CO2 dosing and my DIY LED lamp. I plan to grow Dwarf Hair Grass and a carpet of something like glosso or HC, along with a few less demanding species. The unit that Ive thought currently will have 4 LEDs:
  1. 2x CREE XPE 6500k @650mA
  2. 1x CREE XPE 3500k @650mA
  3. 1x CREE XPE RB(465nm) @650mA
Will this be okay for the plants?
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post #2 of 11 (permalink) Old 08-28-2017, 01:45 PM
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W/ all the LED's on full your color temp is off the chart bluish and your CRI is low at 41..
Fine for plants.
Visually a bit on the low quality side.


Using reg blue in place of royal blue will be an improvement..11490K and 72cri
Dimming the blue and ww to 1/4power will push cri up to 93 (83 if sticking w / RB)

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post #3 of 11 (permalink) Old 08-28-2017, 04:51 PM Thread Starter
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Quote:
Originally Posted by jeffkrol View Post
W/ all the LED's on full your color temp is off the chart bluish and your CRI is low at 41..
Fine for plants.
Visually a bit on the low quality side.


Using reg blue in place of royal blue will be an improvement..11490K and 72cri
Dimming the blue and ww to 1/4power will push cri up to 93 (83 if sticking w / RB)
How do you calculate CRI?
Wouldn't it make more sense to just use 3 6500k LED and one 10000K LED instead of Blue and WW if its affecting CRI that much?
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post #4 of 11 (permalink) Old 08-28-2017, 05:28 PM
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Originally Posted by Ashwin1224 View Post
How do you calculate CRI?
Wouldn't it make more sense to just use 3 6500k LED and one 10000K LED instead of Blue and WW if its affecting CRI that much?
Using this:
SPECTRA

As to the 10000k,6500k ..Yes increases CRI but still short in red..In other words better color rendition somewhere less in other places but average is fairly high..

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post #5 of 11 (permalink) Old 08-28-2017, 06:03 PM
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In a small array of leds, your best bet is to build the light so colors are adjustable/dimmable.

The general strategy used by most manufacturers is a main white channel and three RGB channels. Larger arrays of leds can customize ratios better, but with only a few leds, I don't see a way to do it withoutbeing able to dim colors.

Many nano tanks use high CRI whites.
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post #6 of 11 (permalink) Old 08-28-2017, 06:18 PM Thread Starter
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Originally Posted by ChrisX View Post
In a small array of leds, your best bet is to build the light so colors are adjustable/dimmable.

The general strategy used by most manufacturers is a main white channel and three RGB channels. Larger arrays of leds can customize ratios better, but with only a few leds, I don't see a way to do it withoutbeing able to dim colors.

Many nano tanks use high CRI whites.
So, an array of 4 3W CREE 6500k LEDs would be best?
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post #7 of 11 (permalink) Old 08-28-2017, 06:31 PM
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Originally Posted by Ashwin1224 View Post
So, an array of 4 3W CREE 6500k LEDs would be best?
Best for what?
If you go that route might as well get a high CRI, high K white COB
One 5600k chip

Luminus Devices: XNOVA Studio LED? Series

Quote:
High lumen output
Over 12,000 lm @ 3000K, 25C
Over 13,000 lm @ 5600K, 25C
CCTs, 3000K and 5600K
95 CRI minimum
90 TLCI minimum
2-step MacAdam Ellipse color binning accuracy
Excellent optical emission uniformity and color over angle consistency
Exceptional long term color stability
Superior thermal conductivity for uniform heat spreading
Environmentally friendly: RoHS and REACh compliant
UL certified
$14 at 36W..
https://www.digikey.com/products/en?...00-F2-2&v=1214

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post #8 of 11 (permalink) Old 09-01-2017, 03:26 AM
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I don't think blue LEDs are that needed, there is a ton of blue in most cool white leds. if 4 leds single channel. I would personally do 3x6500k 1xDeep Red. the deep red 660nm is missing from most leds and would actually add something to the spectrum, also on the edge of our perception so doesn't change the color temp all that much.
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post #9 of 11 (permalink) Old 09-01-2017, 03:44 AM
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Originally Posted by Kampo View Post
I don't think blue LEDs are that needed, there is a ton of blue in most cool white leds. if 4 leds single channel. I would personally do 3x6500k 1xDeep Red. the deep red 660nm is missing from most leds and would actually add something to the spectrum, also on the edge of our perception so doesn't change the color temp all that much.

Most base emitters are royal blue not blue..
Actually part of a shift in my thinking over the past couple of years..
White LED's are short in blue to blue green..

Your concept is fine Old Finnex-R was 8000k (maybe 7000k, not sure off hand) and deep red.. Looks fine.
cheap 6500k are just rb w/ yellow broad phosphors..

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post #10 of 11 (permalink) Old 09-01-2017, 04:41 AM
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Quote:
Originally Posted by jeffkrol View Post
Most base emitters are royal blue not blue..
Actually part of a shift in my thinking over the past couple of years..
White LED's are short in blue to blue green..

Your concept is fine Old Finnex-R was 8000k (maybe 7000k, not sure off hand) and deep red.. Looks fine.
cheap 6500k are just rb w/ yellow broad phosphors..
you might be right I'm doing my lights with 50mm Rigid led strips. 11 watt 6500k strips matched to 7watt 5:1 660nm/460nm "plant strips". really nice look to them. very small amount of added blue so prolly somewhere in the low 7k range.
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post #11 of 11 (permalink) Old 09-04-2017, 07:54 PM
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Honestly if you want simple, do as jeffkrol suggested, go with a single high-CRI base white, add a cheap CPU heatsink(with included fan) and run a constant current driver (adjustable or not, your choice) like this and slip something nice over the assembly.

The Luminus Devices chip looks really good on paper, and good pricing too. Slightly less efficient than the Bridgelux or similar offerings but you make up for it in CRI so it's no big deal at all. I'm running a single 5600k 90CRI vero 10 (350mA) with a Cyan (300mA), Blue (700mA), 4000k Neutral white (500mA), and Violet (700mA) on my Nano, and the high CRI makes a big difference compared to simply mixing and matching...


Last edited by Lingwendil; 09-04-2017 at 07:57 PM. Reason: edit
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