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Old 01-06-2017, 01:25 AM
GpsFrontier GpsFrontier is offline
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Join Date: Mar 2009
Location: Lake Havasu AZ.
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Hello newhydro16,
I would use florescent lights myself. I don't know what your spacing is or how much coverage area your trying to get out of the two 45 watt led lights. But each 45 watt light probably wont cover more than one sq foot each. Have a look at this video Low Watt LEDs vs T5 grow lights. For lettuce you'll need a minimum of about 35 watts of LED lighting per sq foot. However with florescent lighting you only need about 27 watts of light per sq foot. That's less wattage for florescent lighting. Four 4 foot T5 bulbs is enough to easily cover a 2x4 foot space and plenty to grow lettuce. each 4 foot T5 bulb is 54 watts x 4= 216 watts total. 216 watts divided by 8 sq ft =27 watts per sq foot.

With that said not all LED's are manufactured the same. Some will preform better, and others worse. To understand why you first need to understand wavelengths of light. Wavelengths of light are different than spectrum of light. Wavelengths are specific, and spectrum's are a range. Red and blue are spectrum's (ranges) of light that are made up of specific wavelengths. Think of it like a radio. FM radio is a range/spectrum of individual wavelengths. Radio stations broadcast on a specific wavelength, and there are a lot of individual specific wavelengths within the spectrum of FM radio. The same holds true for light. You can also think of it like shades of light. While Red is a color there are hundreds of shades of red. Red is the spectrum, but each specific shade of red is a wavelength within the spectrum.

You can't tell how many individual wavelengths of light there are in a specific color. You know you see red or blue, but you can't tell how many specific wavelengths are present in what your looking at, nor can the human eye tell how strong those wavelengths that are there are. So in other words while one red LED light may look just like another, they can be vastly different in actual light output. This is why you really have to research the manufacture of the LED lights to find out if not only do they know what they are doing in manufacturing them, but if they do growth rate, as well as growth quality testing comparisons. Otherwise it's just a crap shoot.

You should also know that each specific wavelength of light affects plant growth differently. Even though it's not commonly known, plants even use wavelengths from the green spectrum of light to build structure. Each individual wavelength of light is used differently by the plant, so they need a good range of wavelengths to grow properly. Many LED lights result in abnormal growth because they don't provide enough range of wavelengths. Again this is why you really need to research the manufactures of the LED lights.

P,S.
You'll be able to tell if your plants aren't getting enough light by looking at the growth. If their getting long and leggy, their not getting enough light. If their growing abnormally small and thin leaves their not getting enough light. If the stems aren't getting thicker and their continuing to grow tall like their going to fall over because the stems can't support the weight, their not getting enough light. Being able to tell if their getting enough range in the wavelengths of light is harder to tell since many of the symptoms can be a result of nutrient balance and/or pH as well.
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Last edited by GpsFrontier; 01-06-2017 at 01:44 AM.
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