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Old 11-03-2010, 01:12 PM
NorEastFla NorEastFla is offline
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Join Date: Aug 2010
Location: North East Florida
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To expand a little on my last post, a 23 watt cfl has 1,380 total lumens output with a 60 lumens per/watt efficiency.

They also have self-contained ballasts that can, if used in an enclose area, result in quite a heat buildup that could heat the reservoir temperature and/or grow chamber temperatures.

Light-bulb efficiency is measured in terms of lumens per watt—the amount of light produced for each watt of electricity consumed. More lumens per watt means more light for your money.

Incandescent: 10-17 lumens per/watt

Halogen: 10-22 lumens per/watt

White led: 20-60 lumens per/watt

Mercury Vapor: 25-60 lumens per/watt

Linear fluorescent: 30-110 lumens per/watt

Compact Fluorescent (CFL): 40-70 lumens per/watt

high pressure sodium (hps): 50-140 lumens per/watt

metal halide (MH): 70-115 lumens per/watt

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Light on a surface (such as a plant canopy) is referred to as illuminance, which is typically represented by footcandles (lumens per square foot, equal to 10.76 lux) or lux (lumens per square meter, equal to 0.092903 footcandles).

Most leafy plants like to have a minimum of 5 thousand lumens per/sq ft of plant canopy. You can get by on 3 thousand per/sq ft, but 5K will make them grow much better and contain much more health giving nutrients and vitamins for your body.

You discover the "Lumens per/sq ft" by adding up the total lumens of your lights and dividing that by the number of square feet of plant canopy you have.

With 6ea, 23 watt CFLs, you have 8,280 total lumens. At the lowest minimum lumens of 3K per/sq ft, that gives you enough light for 2.76 square feet of plant canopy if you expect good growth, short internodal length and average fruiting.

2.7 square feet is the same as an area of 397.44 square inches, or an area about 20 inches by 20 inches.

As you can see, that's not much area. You'll find that HPS is the best all-around lighting for plants indoors. Great spectrum, remote ballasts and a very good lumens per/watt output.

A 150 watt HPS will have about 16,000 total lumens. At 3K per/sq ft, that's enough lumens for an area of 5.33 sq ft or an area of 768 square inches or an area of 28 inches by 28 inches.

An area covered with multiple 150 watt HPS will be much better than an area covered by one larger bulb. The lights can be closer to the plant canopy and each plant receives a much better light and an efficiency of 106.66 lumens per/watt as opposed to the 60 lumens per/watt the 23 watt CFLs will give you. It's a much better bang for your buck.
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