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- Growing Under Lights (http://www.orchidboard.com/community/growing-under-lights/)

- - New CF Light to consider (http://www.orchidboard.com/community/growing-under-lights/7685-cf-light-consider.html)

At our northern latitude, even a south-facing window gets dim light compared to you. Mine are all inside and this of year (winter here) skies are gray a lot.

Grandma M . You could use two, I do. They put out a lot more light at half the cost, so in theory you could raise your fixture and get good light in a larger area, that means more plants, something to ponder. Jim.

Quote:

Originally Posted by jim blanford (Post 70608)

Jim, how many lumens do you figure you get from 2 bulbs? How far away are your plants? I measure about 600-700 foot candles near the Brassias - a bit weak, but far better than I was getting.

These are my measurements, now I don't use lumens I only use FC's.

400 MH............. 2 105W CFL's
12" 1000 fc ...... 12" 1600
24" 600 .......... 24" 800
48" 200........... 48" 400

Right now I use the light for a staging area for plants in spike or bud. the plants are about 24" to 30" below it. I hope you can use some of this info. Jim.

Guys, I'm sorry you are mistaken on your measurements...

Flourescent bulbs (including T5 and Compact flourescents) are not any more efficent than Metal Halide... Both are in the 70-100 lumens per watt range. You are confusing Incandescent with the lumens per wattt.

Why do you think they use Metal halides and High Pressure Sodium bulbs in the streets? Because they are VERY efficent. Flourescent bulbs are NOT any cooler, it's just that the heat is dispersed over a larger area, which in it's self is a good thing, but watt for watt, neither is more efficient. Sodium bulbs are a LOT more efficient than Metal Halide or Floursecent bulbs.

Just because you can feel heat, does not mean that it's not effiecent. A 400w Metal Halide bulb is putting out nearly 32,000 lumens!!!

You will need roughly the same watts in flourescents that you have in metal halide to get the same output. Floursecents would allow you to spread that light out, but the circular spiral bulbs are bad because they lose a lot of light bouncing through the tubes to get out... I don't see a good reason to use the spirals unless it's a retrofit, there are plenty of good alternatives with a good reflector and external ballast. The cheap ballasts on those spiral bulbs usually are the first to go and are wasteful, because basically each time the phosphors in the bulb are used up, you throw away an entire ballast...

example 400w Metal Halide specs:

UMH Series - Metal Halide - General Lighting - USHIO

http://img.photobucket.com/albums/v5...ing/lchart.jpg

http://img.photobucket.com/albums/v5...Efficacies.jpg

I reread the specs on that 105w compact flourescent, and the inital lumen output is 6900 lumens, which means you would need 4.6 of them to equal the same lumens... if you count in relector efficency, and that the spical compacts have a less than optimal way that the light actually reaches the plant, you are looking at ~6-7 of them...

Quote:

Originally Posted by rsfrid (Post 70362)

I just had to do this - made total sense! I updated a 55 watt CF (coily tube bulb) full-spectrum to a 105 watt CF full spectrum rather than go to a second bulb (just re-positioned the bulb). Here's the setup it's the bulb in the front. The two nearest the windows are still 55 watt bulbs. I measured over 600 foot-candles near the screen where the plants set. That's more than a doubling of light. Here's the source for the bulbs (pretty cheap for what they are) 105 Watt Compact Fluorescent I purchased the "full-spectrum bulbs, as they are best for plants.

Can you give me an idea of how far from the light you measured your results what meter you used? 600 ftc at over 1 foot would be a great bulb!

800 FC horizontally at 10" and a bit over 400 FC diagonally down from bottom at 12". I use a Sper Scientific 840020 Lux/FC meter (it's a professional calibratable meter, so very accurate.) They are rated 6900 lumens which is 140% of a single 54 watt 48" t5 bulb. They use a standard socket and run quite cool. Hope this helps.

Quote:

Originally Posted by rsfrid (Post 70832)

I use the same meter! Thanks for the additional information, I'm very interested in measurements of CFLs. I've measured several popular 23w (100w equivalent) bulbs from the bigbox stores.

Quote:

Originally Posted by Ocelaris (Post 70785)

I don't see a good reason to use the spirals unless it's a retrofit, there are plenty of good alternatives with a good reflector and external ballast.

I do. Look at my original picture post. I have no way to do otherwise. Tight space, arrangement of grow area, etc. dictate CF's. I measured 800 FCs with a high quality professional calibrated meter at 10" horizontally from the middle of the coils. This closely matches with Jim's measured 1600 FCs using two bulbs in a reflector. I migrated from a 400 watt MH setup which cost me a bundle, and gave dismal results to this setup with t5 and I'm very happy with the results as are the plants. The most important thing to me isn't the specs and charts and graphs, it's the end result - getting great growth and flowers and I do both. Thanks for your comments. :)