t5 distance question, pleae

[VickiC]

Hi,
This is a carry-over question from a question that I asked you a few weeks ago. After getting your responses from my question to you then and measuring a little more since then, we decided to use 2-4 bulb t5 fixtures...each fixture generating about 20,000 footcandles.

Referring back, my husband has helped me fix up an adjoining room to our garage (which was at one time his electronics shop) for an orchid room for me. The room is approx. 10'x10' with 2 main shelves and some "odds and ends" growing space. The ceiling is approx. 10'. The rough measurement from the ceiling to the top shelf is approx. 6' (I think...keeping in mind that a female is doing the measuring lol) The distance from the top shelf to the lower shelf is approx. 2'. Of course, the lights will be side by side...the length of the shelves. My question to you is: about what distance would you suggest that the lights be suspended from the ceiling down to above the top shelf giving the orchids on that shelf a good amount of light but also shining a sufficient amount of light down to the bottom shelf. My plans are to grow mainly dens and catts (a few Vandas) on the top shelf, and probably some phals, as well as few other different orchids, on the lower shelf. The electrician(s) should be coming tomorrow to do the installation, so I would really appreciate your advice sometime today or tonight, if poss.
Thanks in advance,
Vicki

[Ross]

Where did you find t5 fixtures that generate 20,000 foot candles? I believe that should be 20,000 lux. This would be approx 2000 foot candles 1 foot below the bulbs (at least what I measure.)

I would suspend the light fixtures on the supplied chains such that are 6-8" above tallest plants for top shelf. You still may need additional light for the bottom shelf. If so, then be sure to plan on keeping drips from the top of the lower light.

[VickiC]

Hi Ross,
I guess I'm all mixed up about Lux and Lumens. (remember, a woman's asking you this question lol) Here's the pg. url: Hydrofarm - Hydrofarm FLT54 T5 Fluorescent System, 4 Tube, 46-1/4" x 13" x 2-3/8"


I got my info under "Fixtures Include". It said "20,000 initial lumen output"

Will you check this out, please, and let me know what you come up with?
Thanks,
Vicki








Please let me know your thoughts after you check it out.
Thanks,
Vicki

Originally Posted by Ross

Where did you find t5 fixtures that generate 20,000 foot candles? I believe that should be 20,000 lux. This would be approx 2000 foot candles 1 foot below the bulbs (at least what I measure.)

I would suspend the light fixtures on the supplied chains such that are 6-8" above tallest plants for top shelf. You still may need additional light for the bottom shelf. If so, then be sure to plan on keeping drips from the top of the lower light.

[Ross]

That makes more sense! That's lumens, not foot candles. 20,000 lumens divided by 12.52 = 1598.72 foot candles. On my New Wave unit, it is rated the same as yours, but actual output is 1800 FCs at 6-8". I just installed a 8 tube unit (same brand) 48" and read 3500 FCs at 11". Yours will need to be pretty close to vandas and Cats if this is only source of light. Remember, though, that 1800 FCs over 12-14 hours, steady, is adequate light for top shelf plants (cats, etc.) because it is steady output. Be sure to buy lots of tubes and change them once a year, whether you see dimming or not.

[VickiC]

Oh....I think I understand better now....thanks. I'd like to know more from wherever you got your info, so do you mind sending me a site url....or wherever your conversion info came from?
Thanks again,
Vicki
(See, I told you to remember that you're answering a question that was worded by a woman lol)

Originally Posted by Ross

That makes more sense! That's lumens, not foot candles. 20,000 lumens divided by 12.52 = 1598.72 foot candles. On my New Wave unit, it is rated the same as yours, but actual output is 1800 FCs at 6-8". I just installed a 8 tube unit (same brand) 48" and read 3500 FCs at 11". Yours will need to be pretty close to vandas and Cats if this is only source of light. Remember, though, that 1800 FCs over 12-14 hours, steady, is adequate light for top shelf plants (cats, etc.) because it is steady output. Be sure to buy lots of tubes and change them once a year, whether you see dimming or not.

[Ross]

Originally Posted by VickiC

Oh....I think I understand better now....thanks. I'd like to know more from wherever you got your info, so do you mind sending me a site url....or wherever your conversion info came from?
Thanks again,
Vicki
(See, I told you to remember that you're answering a question that was worded by a woman lol)

OK, one thing at a time. As for lumens output double check your link. It says Lumens, not Foot-Candles.

As for conversion try this web site: Lumens, Footcandles, Candlepower, Measuring Light Output A bit confusing, but if you slowly digest what they are saying, you'll find the formula. Bulbs are rated at the surface of the bulb (the only constant.) A candle power or foot-candle is usually expressed at 1 foot from a bulb. Europeans don't use this term or concept at all, thus the lack of response from overseas. My light meter measures both Lux (the only true measure of light output) and foot-candles (the most popular US term and concept). Once you know light output in LUX or Lumens, it's pretty easy to convert. Light falls off at a square of the distance from the source. So light at a bulb surface will be double that at 1 foot, etc. Does this help? If not, get a really accurate light meter and go from there till you are comfortable : Sper Scientific Light Meter Lux & Foot Candle | Technika

[Vanessa]

Thanks to Ross in an older post about light distances I ordered one of these guys. It has helped me tremendously with my T-5 light banks positioning and also with sun coming thru windows with window tint and sun levels at different times of year. It's a very good investment.

[VickiC]

Thanks for replying. Yes, Ross seems to be very good at light info.

When I click on the url you sent me that should take me to your gallery, the msg. pops up and says "The webpage cannot be found". Why do you think it says that? I really wanted to see your gallery, so if you don't mind, I would appreciate it if you will give me your thoughts on what might be the problem.
Thanks,
Vicki

Originally Posted by Vanessa

Thanks to Ross in an older post about light distances I ordered one of these guys. It has helped me tremendously with my T-5 light banks positioning and also with sun coming thru windows with window tint and sun levels at different times of year. It's a very good investment.

[Ross]

Originally Posted by VickiC

When I click on the url you sent me that should take me to your gallery, the msg. pops up and says "The webpage cannot be found". Vicki

Which URL is that? My gallery can be reached via the camera button in upper right across from my name. If you mean my Orchid Blog, google blogs goes down for maintenance lots of times. I just checked both and they come up fine.

[VickiC]

Hey Ross,
I meant Vanessa's gallery. I had already looked at yours sometime back. I was very impressed with your orchids, as well as your home and growing areas.....very nice! You have obviously put a lot of work into everything.

By the way, the electricians are installing my lights now. After I read your post to me about the lighting output I would get from them, I knew then that I was gonna have to get some supplemental lighting, so I have been discussing that with them....as to what I will need to suppliment them, as well as where in the room would be best for them to be installed.

Anyway, would you and Vanessa mind clicking on the link to her gallery and see if you come up with the same error msg. that I did? If you will, please let me know.

Best I get out there and crack my whip so these guys will get on the stick more. lol

Thanks again,
Vicki

Here's the link to Vanessa's gallery:
http://www.orchidboard.com/community...my_gallery.jpg

Originally Posted by Ross

Which URL is that? My gallery can be reached via the camera button in upper right across from my name. If you mean my Orchid Blog, google blogs goes down for maintenance lots of times. I just checked both and they come up fine.