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Post by brewcat on Dec 8, 2011 2:55:47 GMT
I'm building a lighted stand for some struggling Neps and orchids. There are T5 4-bulb four-foot fixtures available locally for $100 (compared to $150 for comparable "grow" light fixtures). What might/would the difference be, assuming equivalent bulbs?
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Post by jesser on Dec 8, 2011 12:00:27 GMT
What might/would the difference be, assuming equivalent bulbs? The main differences I may think of may be: - durability/quality of the electronic ballast - radio interference suppression of the electronic ballast - trading margin Very cheap T5 ballasts may burn out after some months of usage and if the radio interference suppression is neglected, they may cause radio interference to wireless and mobile phones, WLAN, bluetooth and other wireless devices used in the surroundings. The electronic ballast built into the fixture is the component that is significant for the quality (and the price) of the fixture alltogether. They are not all the same. |
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Post by RL7836 on Dec 9, 2011 21:47:42 GMT
Also, check that for a true mirror reflector. I suspect that all 4' fixtures are HO - but best to check.
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Post by brewcat on Jan 7, 2012 15:52:51 GMT
So now I've noticed that warmer-spectrum bulbs I'm finding ("natural" or "warm" compared to "cool") have significantly less lumen output. Is this always the case, and for the nerds, anyone know why?
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Post by av8tor1 on Jan 8, 2012 22:34:35 GMT
Lumens are a measurement of light intensity as it appears to the human eye. Being such, it is biased toward the green and yellow portions of the visible light spectrum. This makes it a poor measurement of how well the light will grow plants. A better metric would be PAR and PUR but these are rarely a known variable. While plants do use yellow and green, they use red and blue wavelengths to a higher degree. I have grown beautiful Cp's using what would be considered very low lumen bulbs. Here is a basic, but good introduction to plant lighting bluegrasscarnivores.com/research1/grolux.pdfHere is a ref that I consider the single best page I have ever read on plant lighting. Caveat, it is oriented toward the planted aquarium crowd and it is from the pre-T5 era.... but the article is still one of the best there is. bluegrasscarnivores.com/research1/comparison.mhtMost any "white" light will grow plants if the intensity is great enough.... but there can be a major difference in how well they grow plants. There is a lot of semi correct/false "tribal knowledge" when it comes to plant lighting.... do your homework and get the best lighting you can. No other variable can make up for poor lighting. Also, good quality reflectors are critical. Two thirds of a linear fluorescent bulb is pointed in the wrong direction. This is usually one of the main cost cutting areas found in inexpensive fixtures. They should be mirrored, there should be a reflector region for each bulb and they should focus the bulbs energy down onto the plant. Many will have a faceted or parabolic type shape and be highly polished (mirrored) aluminum. Why buy a cheap fixture that will waste 2/3rds of the light and electric cost. Where is the savings in that  Av |
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Post by brewcat on Jan 9, 2012 2:18:23 GMT
Well, if I could afford to target PAR and didn't care about viewing I'd get LEDs  . But I am using HO T5s (which do have good reflectors). |
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Post by av8tor1 on Jan 9, 2012 18:34:00 GMT
good move....
Even PAR and PUR is still only part of the story. Green is needed for canopy penetration while other wavelengths are needed for this or that.
IIRC, one wavelength suppresses Botrytis while another stimulates Trichoderma sporulation, etc.
Just focusing on red and blue isn't enough long term IMHO
Butch
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Post by walberg on Jan 20, 2012 10:34:28 GMT
good move.... Even PAR and PUR is still only part of the story. Green is needed for canopy penetration while other wavelengths are needed for this or that. IIRC, one wavelength suppresses Botrytis while another stimulates Trichoderma sporulation, etc. Just focusing on red and blue isn't enough long term IMHO Butch yes thats correct and also the reason i use led systems with not only red and blue but also, green yellow and uv. I hav 106 watt system and the results are better than as with 2 x 80 watt dulux lights. |
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. But I am using HO T5s (which do have good reflectors).
