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Newbie LED questions.


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Old 10-18-2013, 09:00 PM
TimeWasteing TimeWasteing is offline
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Default Newbie LED questions.

I'm building a 4 foot(L) x 4 foot(W) x 6 foot(h) grow box that I plan to grow 1-2 tomatoes and maybe 1-2 peppers (winter hobbie). I've got someone building me a 35red(655-660nm)/5blue(450-455nm) 1w led light (basically a PCB in a box with a 80mm computer fan) nether of us really know much about plants so I figured I better ask for help.

1. I've read red/blue is the better wavelengths to get but would it hurt to mix in other wavelengths? let's say I want to add 30-45/1w~ white led's.

2. what len degree should i use? being in a small enclosed box could I just go with no len's?

3. Placement of lights? My plan is to have a 40x1w led as the top and 2x13+watt cfl bulb (or small 12-15 watt led) on 3 of the 4 sides.

4. would 3w/other led's be better?

5. Does the PCB need a better/2ndray heatsink? It's on a thin aluminum heatsink plate I'd say 2mm thick.


Last edited by TimeWasteing; 10-19-2013 at 12:03 AM.
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Old 10-19-2013, 05:30 AM
GpsFrontier GpsFrontier is offline
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Hello TimeWasteing,

Quote:
1. I've read red/blue is the better wavelengths to get but would it hurt to mix in other wavelengths? let's say I want to add 30-45/1w~ white led's.
Red and blue are the dominate color spectrum's. But there many wavelengths within any color. Also not just any LED works fine. You need to use high output LED's, and I'm not sure about the circuit board (chip). Also you will need to use a "LOT" of led's to grow plants that grow more than 6-10 inches tall.

Quote:
2. what len degree should i use? being in a small enclosed box could I just go with no len's?
A len's focuses the light into one area. If you want one part of the plant to grow and not the rest, focus the light in that area.

Quote:
3. Placement of lights? My plan is to have a 40x1w led as the top and 2x13+watt cfl bulb (or small 12-15 watt led) on 3 of the 4 sides.
You want the light distribution to be as even as possible. As the plants grow, the light angles will change. Shaded leaves cant conduct photosynthesis (especially for fruiting plants), and the more leaves the more shade the plant provides to the inner leaves.

Quote:
4. would 3w/other led's be better?
Realistically, If you want to grow plants that would normally take 400 watt MH or hps bulbs, you'll need a lot more than 3 watts of LED's. Realistically you'll need close to (if not more) actual wattage in LED or CFL. When I say CFL wattage, I don't mean the bulb comparison output, I mean the actual energy consumption (with LED's too). Both LED and CFL lighting don't have nearly the light through as MH or HPS. When I say light through, I mean that the light intensity (lumen's) drops significantly after a foot or two compared to MH or HPS. The light through for MH and HPS is 4-5 times that of LED and CFL.

Just my two cents...
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Old 10-19-2013, 12:28 PM
TimeWasteing TimeWasteing is offline
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They should high powered 1w led's atlest they were advertised as that. I'm know there are better ones but these should work.

Being in a small box the plant should only be 18-24 inches away from each light. *I can lower the top light

Though I read lumen weren't key when it comes to led's? something about PAR/nm they give off.

So your saying I should get 400 watts (used) worth of led's/cfl? I'm not going for best possible growth just effective/worthwhile would 85led+78cfl (should be 140-150w~ used) do? I've seen others topic/video's were people have grown tomato's under 90-120~ watt's in a 3x3-4x4 area.

Last edited by TimeWasteing; 10-19-2013 at 05:36 PM.
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Old 10-20-2013, 06:52 AM
GpsFrontier GpsFrontier is offline
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Hello TimeWasteing,
Quote:
Though I read lumen weren't key when it comes to led's? something about PAR/nm they give off.
The light output is always important, and a main factor for plant growth. PAR and NM are both the same thing as lumen's. Their all measurements of light output. The higher the par output, the higher the lumen and nm output will be. The higher the lumin output the higher the par output will be. And you can say the same thing for the measurement "candle power" The higher the candle power, the higher the lumen and par measurements will be. Candle power, par, nm, and lumen's are just different measurements for the same thing "light intensity." The same way you can choose to either measure something in feet and inches, or in centimeters and millimeters. It wont change the distance of something witch form of measuring choose to measure it with.

Quote:
So your saying I should get 400 watts (used) worth of led's/cfl? I'm not going for best possible growth just effective/worthwhile would 85led+78cfl (should be 140-150w~ used) do? I've seen others topic/video's were people have grown tomato's under 90-120~ watt's in a 3x3-4x4 area.
I used 400 watts as an example. I could have just as easily used 1000 watts or 200 watts in the example. The hype LED manufactures base their propaganda on is largely unfounded. They try and tell people that they can replace a 400 watt light with a 30 watt LED and get the same or better results using less energy. But it just doesn't work that way, and that's what I was trying to get across.

I know your not trying to win any blue ripens, but if you want effective/worthwhile producing plants, you should consider what makes them produce worthwhile produce. Fruiting plants need a lot more light to produce worthwhile fruit (2-3 times as much) than non fruiting plants like lettuce. I'm not sure what variety of tomato's and peppers your planing on growing. But even bush varieties of both can get 4-5 feet tall and just as wide given a good growing environment. And indeterminate types can grow tall as a house and 5-6 feet wide. And sure if you constantly trim your plants back so they don't get bigger than a foot or two tall and wide, sure a 100 watt MH/HPS bulb should work fine. So a 90-120 watt LED is replacing a 100 watt bulb. Witch was my earlier point. Your not saving much if any energy.

Also to consider is the size of the grow box wont be the size of the plants. In your case a 6 foot tall space, you'd be lucky to get a 3 foot plant in it when you consider the space needed at the bottom for the hydroponic system, reservoir, root space, air circulation fans etc. not to mention the space needed at the top for the lights, and space between them so the foliage doesn't burn. Again I don't know what varieties your planing on growing, but you'll likely find that your plants will outgrow the space before you even get any fruit off of them.

YA, if you want those plants to produce you'll need good air circulation inside the box. Not blowing fresh air in, but circulation within the box to distribute the pollen from flower to flower. Blowing the air out of the box just blows the pollen away from the flowers you want pollinated. Also if you don't have good air circulation the humidity in the box could cause fungal problems on the plants. Air circulation is very important.
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Last edited by GpsFrontier; 10-20-2013 at 07:03 AM.
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  #5  
Old 03-21-2014, 01:35 PM
HydroMan HydroMan is offline
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I was thinking about getting an LED setup, but I am kind of new to LEDs... They are supposed to take up a lot less power as compared to florescent, right?
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Old 03-21-2014, 07:24 PM
TimeWasteing TimeWasteing is offline
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Hello HydroMan, I've done a little more research and basically what I've learned is:

The white leds are a bit better (like 3% more effective per watt) then florescent but the point of LEDs is the use the targeted wavelengths (red blue ect) that the plant your growing needs/prefers (making it more effective per watt used). White is the lest effective color (look up "PAR" ).

Some plants like marijuana can do well with just red/blue LEDS while others could use a 3rd-11th~ wavelength.



I've got half my grow box in red/blue (100x1w leds) and the other half with warm/cool white (100x1w leds) LED's I can't really tell a difference but the lights kinda mix.

*I'm growing dwarf tomatoes and peppers in a 4x4 box not the most light depending plants.

Last edited by TimeWasteing; 03-21-2014 at 07:32 PM.
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Old 04-04-2014, 03:16 PM
HydroMan HydroMan is offline
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Thanks TimeWasteing,

So if I understand you correctly, then by targeting specific wavelengths, you can get the same effect as you would with a higher wattage light that doesn't target.

Also, I was looking at this 28 watt Grow Light or this 90 watt UFO Grow Light. Now, both are targeted as you say, but one is 90 watts and the other is 28 watts.

The thing at confuses me is that the 28 watt one looks bigger than the 90 watt UFO Grow Light. Is it that the LEDs in the UFO style one are brighter? I don't know...

Thanks for your help, bro!

Last edited by HydroMan; 04-04-2014 at 03:29 PM.
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Old 04-04-2014, 06:00 PM
TimeWasteing TimeWasteing is offline
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The 28watt'er uses fractional leds (less then 1 watt each) while the other uses 3w LED's.

The fractional leds just have no penetration and only the top leafs will get light.
*would work with small herbs and maybe lettuces?

Most people (from what I've read) suggest 3watt LEDs b/c the better penetration. I personally use 1w led's (b/c they were cheap/easy to build) they seem to do fine on my small plants (less then 2 foot tall).

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