New CF Light to consider

[Ray]

Ocelaris - how old is that relative efficiency graphic?

CFL's have become a great deal more efficient than the old standard T18 fluorescent tubes, both in terms of energy transfer from electricity to phosphor, and in the output of that phosphor once excited.

[FinnBar]

the sodium vapor lamps are used as streetlights because of their high light output, not the spectrum. i'd argue that in our purposes you get same results with full-spectrum CFLs and far less lumens than SV. besides, the Dulux 55W puts out 4800lm. that's over 87lm/w.
at 400W the output would exceed 34900lm.

[Ocelaris]

Originally Posted by Ray

Ocelaris - how old is that relative efficiency graphic?

CFL's have become a great deal more efficient than the old standard T18 fluorescent tubes, both in terms of energy transfer from electricity to phosphor, and in the output of that phosphor once excited.

Ths first chart is a little dated, but the second is accurate. There still is not a flourescent bulb which matches the high wattage metal halides. even my 100w metal halide bulb is 93 lumens a watt, and the higher you get, the more efficient you get... of course, anything bigger than 200w metal halide and you are getting a TON of heat... I wouldn't use a 400w Metal halide except of a fish tank where water absorbs the light and you need a penetrating light source.

I understand heat = bad, people don't want and are intimidated by HUGE expensive metal halides... me too, I don't use them, I use 100-150w bulbs and they're great. I think people have the wrong impression of them, and I'm here to show that you can use metal halides and Flourescents both in tandem where each is beneficial.

Flourescent bulbs have improved phenomenally since T12s, but the limiting factor which they have been improving is basically the size of the bulb, which Metal Halides have always been at an advantage. The main reason a T-5 is more efficient than an already efficient T-8 is because of the diameter of the bulb. As the surface area of the bulb decreases linearly, the light output grows squared... literally, it's not phosphor or better ballasts or filaments, it's just the size of the lamp. I'm not saying that there are no improvements from T-8 to T-5, but they are minimal compared to the circumference of the lamp. T-8 = 8 * .25" = 2" circumference, T-5 = 5 * .25" = 1.25" circumference. Metal Halides are basically the pinnacle of a point source of light, in this respect they are more efficient. The reason is restrike. The light from the inner phosphors shoot outwards more often than not in a smaller diameter tube than in a larger one. Once the light goes out of the phosphor, if it has to restrike thorough the glass, ALL light is lost. So a smaller tube or point source fixes this problem.

RSFrid, I can understand for the purpose of your room, but I could also reccomend a 100w metal halide bulb which mine puts out 8200 Lumens, and lasts 20000 hours with a CRI of 92... Compared to 6900 lumens 80 CRI and 8000 hour life span. I'm just trying to break the "big, bulky, hot, and expensive" myth of metal halides... they're just two different technologies, and just because most of us are familiar with the greenhouse varieties, doesn't mean we can't use the smaller versions for our own purposes of indoor orchid growing.

You could hang the Medium based Metal Halide bulb in the same manner that you hung the compact flourescent, and it will actually be cooler than the flourescent bulbs becausae it has a higher lumen/watt ratio. I picked up a 100w metal halide setup on ebay for 40$ shipped with everything included. That was a good find, but it's not unreasonable to find it for 60-70$ And if you're conscious about the environment, you can be happy that after 8,000 hours you will not be throwing away an entire ballast. At least seperate the bulb/ballast, no sense in spending half the cost of the bulb on electronics you throw away.

Metal halide CAN be cheap, and cool, and I think people in this thread confused metal halides and incandescent efficiency. They thought "100w compact flourescent = 500w bulb" well a 500w INCANDESCENT or HALOGEN (filament bulb) is only 20 lumens per wattt... but a Metal Halide is on par or better efficiency than flourescent... but flourescents are packaged and sold in much more convenient and useful forms... who needs a 400w metal halide inside??? very few people because the heat is so great. But it is difficult to find a 100-150w metal halide cheap like you can flourescents... sad, because they are such a useful trick when you need a point source of light. I can find them on ebay, but not everybody likes that sort of thing.

Flourescent is a great technology, I use compact flourescents and T-5s often. Flourescents (including Compact Flourescents) and Metal Halide are both non-linear spectrum bulbs, and both are rated on a CRI basis. If you compare metal halide to flourescent "full spectrum" you will find there are equally good if not better metal halide options. Example this 100w Phililps Master color 100w Metal halide bulb I am using, 25$ and 20,000 hour life span. 92 CRI (really really good)...

http://www.prismaecat.lighting.phili...CL_ALTO+FB.pdf

It's a little bit more work to set up, and I can understand why people would hesitate, but there are a lot of sites and people out there who have done the wiring themselves and been very successful including myself. Honestly flourescents are a lot more complicated wiring... I just don't want people ignoring a promising technology because of confusion, and I hope that comes out in my posts. Cheers, Bill

[LinhT]

I'm looking to order from the site Ross suggested. However, just want to know if it's necessary to get four 5000k full spectrum CRI 80 bulbs at 105W each for low light orchids like phals? Or is it possible to go down on the wattage to about 26W? I only have four plants...

[FinnBar]

just want to know if it's necessary to get four 5000k full spectrum CRI 80 bulbs at 105W each for low light orchids like phals?

considering the amount of plants definitely not.
one 105W is plenty for four Phals.
i think it's a better idea to get one of those rather than 4 lower wattage bulbs.

[goodgollymissmolly]

I would probably be wise to avoid this discussion, but no one ever accused me of being smart. There are all kinds of misconceptions being confused here.

Let's take on a couple of items. The apparent belief that CFL bulbs are the greatest thing since Swiss cheese is just wrong. It largely stems from the industry and government push to replace incandescent bulbs with more energy efficient flourescents. In order to facilitate this change the new type bulbs need to be direct replacements for old incandescent bulbs so that all the fixtures in use do not require replacement. Ocelaris is completely correct in pointing out that this requires the ballast to be a part of the replaceable bulb which is pretty wasteful of both your money and natural resources, but effective in getting people to change. He is also absolutely correct in pointing out that if we started from scratch (where no one owned existing fixtures of any kind), we would not design bulbs in the CFL style because it is not the best design choice for light. It just happens to be practical in terms of utilizing current fixtures.

Let's talk CRI (Color Rendering Index). It's a way for the industry to describe how colors appear to the human eye under the light in question. 100 is so-called "perfect". Well, by definition, 100 is what you see under an incandescent bulb, in other words at a color temperature of about 2700K (very reddish yellow), not what you would see in daylight as many of you think. Secondly, it says nothing about the wave lengths in the output spectrum. The human eye can perceive the same color from infinite mixtures of wave lengths, just ask your camera which sometimes gives strange results when you least expect it. There is no claim that the spectral output is useful for plants.

Lastly, for now, let's talk total light output. Chlorophyll absorbs in the blue range (about 380-420 nm) and in the red range (around 680nm). In a complex reaction it converts water and carbon dioxide to oxygen and carbohydrates which subsequently feed the plant. Light in the center of the visible spectrum is green. Plants look green because they reflect (do not use) green wavelengths. No matter how much light intensity you shine on your plants, they only benefit from the wave lenghts that they can utilize. When you read light requirements in a cultivation recommendation they are talking about sunlight which contains a full spectrum of all wave lengths with roughly equal portions of red, green and blue. Flourescents have huge spectral gaps in their outputs.

No matter how long this discussion continues, the fact remains the same. High pressure sodium lighting with spectral shifts created by surface coatings (sometimes called "Agro" bulbs) are the most efficient at producing light from energy input and in producing light useful for plants. Yes, you can grow plants in flourescent light, but you need to pay careful attention to the spectral characteristics of the bulbs you are using. CFL's are a utilitarian choice, but not the best choice from a purely efficiency or plant growth standpoint.

[Ocelaris]

Top notch info