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Old 08-26-2013, 05:58 PM   #1
hiddenPenguin
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LED spectrum?


Looking to build LED fixture equivalent to 4x 18W CFL.

Going over sump so looks don't matter.

Need maximum feasible efficiency because of high energy costs (for comparison purposes use $0.36/kWh).

Questions:
-Wavelength - look for 660nm and 440nm reds and blues?
-Thinking 16x 3W LEDs - is this realistic?
-What is the best ratio of red:blue (or other colors) for removing nutrients from the water?
-Do plants actually need other wavelengths of light? (such that giving only red and blue would be like feeding only N and P while ignoring K and micronutrients)
-What are some good bulbs and drivers? Especially concerned with efficiency of the driver.
-Budget: $70 if nondimmable; $90 if dimmable. (Payback period is short enough to be competitive with CFLs below this cost)
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Old 08-26-2013, 07:05 PM   #2
jeffkrol
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Quote:
Originally Posted by hiddenPenguin View Post
Looking to build LED fixture equivalent to 4x 18W CFL.

Going over sump so looks don't matter.

Need maximum feasible efficiency because of high energy costs (for comparison purposes use $0.36/kWh).

Questions:
-Wavelength - look for 660nm and 440nm reds and blues?
-Thinking 16x 3W LEDs - is this realistic?
-What is the best ratio of red:blue (or other colors) for removing nutrients from the water?
-Do plants actually need other wavelengths of light? (such that giving only red and blue would be like feeding only N and P while ignoring K and micronutrients)
-What are some good bulbs and drivers? Especially concerned with efficiency of the driver.
-Budget: $70 if nondimmable; $90 if dimmable. (Payback period is short enough to be competitive with CFLs below this cost)
1)Sure
2)How big is the sump? Seems overkill
3)???? 3-6:1 R/b
4)It depends plants can use other colors for other things (carotenoids/hormones) and even green if saturated w/ high light
5)Meanwells are fine .. Steves LEDs are better
6)Cutting it close w/ quality LED's@ your orig size.. Power supply would run $30... Drivers $14
aluminum $20ish depending
fans?
Dimming controller??

Quote:
200 - 280 nm UVC ultraviolet range which is extremely harmful to plants because it is highly toxic.
280 - 315 nm Includes harmful UVB ultraviolet light which causes plants colors to fade.
315 - 380 nm Range of UVA ultraviolet light which is neither harmful nor beneficial to plant growth.
380 - 400 nm Start of visible light spectrum. Process of chlorophyll absorption begins. UV protected plastics ideally block out any light below this range.
400 - 520 nm This range includes violet, blue, and green bands. Peak absorption by chlorophyll occurs, and a strong influence on photosynthesis. (promotes vegetative growth)
520 - 610 nm This range includes the green, yellow, and orange bands and has less absorption by pigments.
610 - 720 nm This is the red band. Large amount of absorption by chlorophyll occurs, and most significant influence on photosynthesis. (promotes flowering and budding)
720 - 1000 nm There is little absorption by chlorophyll here. Flowering and germination is influenced. At the high end of the band is infrared, which is heat.
1000+ nm
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Old 08-26-2013, 08:04 PM   #3
gus6464
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Quote:
Originally Posted by jeffkrol View Post
1)Sure
2)How big is the sump? Seems overkill
3)???? 3-6:1 R/b
4)It depends plants can use other colors for other things (carotenoids/hormones) and even green if saturated w/ high light
5)Meanwells are fine .. Steves LEDs are better
6)Cutting it close w/ quality LED's@ your orig size.. Power supply would run $30... Drivers $14
aluminum $20ish depending
fans?
Dimming controller??
^

If you want an even simpler answer these are the three LED's that will hit the peaks.

420nm Violet
450nm Royal Blue
660nm Deep Red
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Old 08-26-2013, 09:44 PM   #4
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Maybe a simple answer

http://www.frys.com/product/6193999?...H:MAIN_RSLT_PG

No power supply or drivers needed, just 120 VAC. May have a wider range of input voltages, I haven't tried.
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Old 08-27-2013, 06:10 AM   #5
hiddenPenguin
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Quote:
Originally Posted by jeffkrol View Post
2)How big is the sump? Seems overkill
The refugium area is 11x17 inches. Pretty sure the PAR would still be much less than sunlight.

Quote:
Originally Posted by jeffkrol View Post
5)Meanwells are fine .. Steves LEDs are better
6)Cutting it close w/ quality LED's@ your orig size.. Power supply would run $30... Drivers $14
aluminum $20ish depending
fans?
Dimming controller??
Thank you, I will check Steves. I know my budget's cutting it close, but if the budget was comfortable then that would mean I've been unnecessarily wasting electricity for a while. I'm basically at the tipping point to start switching from fluorescent to LED, as LED performance per dollar improves.

Quote:
Originally Posted by gus6464 View Post
these are the three LED's that will hit the peaks.

420nm Violet
450nm Royal Blue
660nm Deep Red
Thanks, in that case how many violets?

Quote:
Originally Posted by ckraft View Post
Maybe a simple answer

http://www.frys.com/product/6193999?...H:MAIN_RSLT_PG

No power supply or drivers needed, just 120 VAC. May have a wider range of input voltages, I haven't tried.
Sorry but I have a feeling that bulb is overpriced junk, and there is no evidence on the product page to indicate otherwise. But thanks for trying anyway.
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Old 08-27-2013, 06:56 AM   #6
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Quote:
Originally Posted by hiddenPenguin View Post
The refugium area is 11x17 inches. Pretty sure the PAR would still be much less than sunlight.


Thank you, I will check Steves. I know my budget's cutting it close, but if the budget was comfortable then that would mean I've been unnecessarily wasting electricity for a while. I'm basically at the tipping point to start switching from fluorescent to LED, as LED performance per dollar improves.


Thanks, in that case how many violets?
In a refugium that small 6 LEDs is all you need. Here is a super cheap solution.

2x of each color from Steve's = $18
1x mean well ldd1000hw $6
1x 12v 1a power supply <$10

Take each set of 3 LEDs and wire them in series. Then you are going to take the 2 sets and wire them in parallel to the ldd. That will put a 11v .5a load on the power supply give or take. If you can find a cheap heatsink the whole thing will be like 40 bucks.



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Old 08-27-2013, 10:18 AM   #7
hiddenPenguin
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Quote:
Originally Posted by gus6464 View Post
In a refugium that small 6 LEDs is all you need. Here is a super cheap solution.

2x of each color from Steve's = $18
1x mean well ldd1000hw $6
1x 12v 1a power supply <$10

Take each set of 3 LEDs and wire them in series. Then you are going to take the 2 sets and wire them in parallel to the ldd. That will put a 11v .5a load on the power supply give or take. If you can find a cheap heatsink the whole thing will be like 40 bucks.



Sent from my Nexus 7 using Tapatalk 4
Thanks, I'd probably still scale it up. I forgot to say, the tank is 125 gallons and I'm not convinced that 6 leds can power enough growth to get rid of all the nitrate.

And if the light requirement really was that small, the savings from using LED over CFL isn't worth the effort.

So anyway you'd recommend more purple/blue than red?

Also, doesn't parallel LEDs risk runaway failure?
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Old 08-27-2013, 12:57 PM   #8
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Quote:
Originally Posted by hiddenPenguin View Post
Thanks, I'd probably still scale it up. I forgot to say, the tank is 125 gallons and I'm not convinced that 6 leds can power enough growth to get rid of all the nitrate.

And if the light requirement really was that small, the savings from using LED over CFL isn't worth the effort.

So anyway you'd recommend more purple/blue than red?

Also, doesn't parallel LEDs risk runaway failure?
No purple blue AND red... More red the better.
Parallel strings are much less a problem w/ constant current drivers..
I have, as an example 1 string of 1W LED's w/ 5 in series and 3 parallel strings.
Due to a bad soldering job (I orig. thought I could save money by ordering heat sink stars and raw diodes separately..ended up not being worth the hassle).. Lost 2 diodes on different branches.. lone string didn't fry... Don't ask me how that works though.. but it seems to. If your really worried there are balancing circuits or even simple fuse on each branch that are an easy fix for this..

also you can mitigate the problem by choosing a driver and parallel string count as to under drive the LED's (best anyways since LED's get less efficient as to reach max current)
slightly. W/ enough parallel strings even losing one will only increase the current on the remaining enough to just boost, not fry them..

Say you have a 1.2A driver and are running 4 parallel strings at roughly 300mA per string (w/ 350mA LEDS w/ tolerance up to 500mA)
Losing an entire string will only cause 1.2A into 3 causing them to go from 300mA to 400mA.. not enough to pop them..

also you need to watch the Vf of the individual colors since they can vary enough to be mildly problematic.. Best to match Vf to a driver. though not necessary if you know what you are doing, it makes things simpler...
Reds tend to have a much lower Vf than other LED's ..

Quote:
Emitting Colour: Red
Color Wave Length: 650-660nm
Reverse Voltage: 5.0 V
DC Forward Voltage: Typical: 2.2V Max: 2.4V
DC Forward Current: 750mA
Quote:
3W blue high power led lamp 440nm~460nm for the aquarium light,3.0-3.6V
sticking w/ R/B for a minute (add purple later.. You would possibly do 12-660nM red and 4 440nM blue.
(4x3.3=13.2V @ 750mA, you could use a 12V driver @700-1000mA all LED's in series)
(12x 2.2= 26.4V @ 700mA driver all in series.. no need for any parallel strings but 2 drivers..)

Add Violet to the blue string
Quote:
Emitting Colour: Ultra Violet
Color Wave Length: 420-425nm
Reverse Voltage: 5.0 V
DC Forward Voltage: Typical: 3.6V Max: 3.8V
DC Forward Current: 700
Adding 4 to the blue string will only push your V to 24V approx (I'd do 3 for a total of 7 @700mA driver )..

any errors/omissions here others are free to correct..

57W of targeted LED's should be plenty..

Last edited by jeffkrol; 08-27-2013 at 02:14 PM.. Reason: add violet
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Old 08-27-2013, 06:33 PM   #9
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Is this for macroalgae? If so just blast them with red. Reds are very powerful so you need a fraction of them vs other colors and you will have a macro farm quick.
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Old 08-28-2013, 10:17 AM   #10
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@jeffkrol:
OK I was under the impression that 1:1:1 of red:blue:violet (1:2 of redblue+violet)) was being recommended.
So 3:1 of red:blue?
Or 3:1:0.75 of red:blue:violet (3:1.75 of redblue+violet))??

So parallel strings is reasonably safe as long as each string has the same total Vf?

Quote:
Originally Posted by gus6464 View Post
Is this for macroalgae? If so just blast them with red. Reds are very powerful so you need a fraction of them vs other colors and you will have a macro farm quick.
No it's freshwater. Not sure what I want to grow yet. Hopefully something edible.


I was browsing on Steves LEDs and saw a 12W royal blue. They didn't have it in red though (only 450nm royal blue and 5000k neutral white). Would something like 12x 3W deep reds and 1x 12W royal blue work?


Anyway it looks I'm going to have to do a more thorough design/calculation, could take weeks.
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Old 08-28-2013, 01:52 PM   #11
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Quote:
Originally Posted by hiddenPenguin View Post
redblue+violet))??

So parallel strings is reasonably safe as long as each string has the same total Vf?


I was browsing on Steves LEDs and saw a 12W royal blue. They didn't have it in red though (only 450nm royal blue and 5000k neutral white).


Anyway it looks I'm going to have to do a more thorough design/calculation, could take weeks.
Well voltage match is for 1)between LED types to avoid over amping one. Parallel strings CAN have different voltages if you use resistors as a voltage drop.. to balance everything out..
To do everything the easiest way..Try to go all serial.. but you have voltage limits (i.e. shouldn't do 25 3.3v LED's in series since the additive voltage would be 82.5V DC
Use "many" parallel strings (and many LED per string) if you need to in order to keep the whole array from going in the event of a string or individual LED failure..
Quote:
Would something like 12x 3W deep reds and 1x 12W royal blue work?
Sure.. 1:1 2:1 3:1 all work.. As noted for "strictly" growth a higher ratio of red to blue is "recommended"..(6:1)
B
Quote:
The short version is that "most higher plants and green algae have highest photosynthesis rate in orange and red lights, secondly in blue-violet light, and minimum in green light." (Zheng, J., Hu, M.J., & Guo, Y.P., 2008)
There are several kinds of chlorophyll, which all serve similar functions. For normal plants, chlorophyll a and chlorophyll b are the main workhorses of photosynthesis. As
can be seen on the graph below, chlorophyll a uses a range of light colors, with peaks at approximately 430nm and 662-700nm. Chlorophyll b uses a similar range, with peaks at approximately 453nm and 642-680nm (eg.,Shibata, K., Benson, A.A. & Calvin, M., 1954; Brown, J.S. & French, C.S., 1959).Chlorophyll d serves a similar function for certain algae. There are also auxiliary pigments which use smaller sections of light. These include beta-carotene which uses small sections of the blue-violet range.
UT on a strictly scientific basis :
https://growblu.com/led-grow-lights-perfect-spectrum

Quote:
Aside from a few species-specific ratios, a red-range-to-blue-range ratio of 7:1 or 8:1 for most food-crop species, with 19:1 being seen as the bare minimum of blue

Last edited by jeffkrol; 08-28-2013 at 02:11 PM.. Reason: addendum
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Old 08-28-2013, 05:36 PM   #12
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Thanks jeffkrol for finding that article, good info.

Unfortunately I did some more (still kind of rough but better than earlier) calculations and it turns out I'd very likely need EVEN MORE LEDs, and so the payback period is definitely too long to be worth it, especially considering the downward trend of LED prices over time.

Better to go with CFLs and wait to upgrade when LEDs become cheaper.
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