reflected footcandles - Orchid Board

VickiC · #1 01-22-2009, 07:55 PM

Hi,
My question is not a "light bulb" question, so I'm hoping that I'm posting to the correct forum. Whatever the case, though, I feel sure you can help me with an answer.

My husband covered all of the counter tops and a portion of the walls of my orchid room with an aluminum foil type insulation material in hopes this would increase my T5s footcandle readings (sorry....I don't know the correct name of the insulation)

. Approx. how many additional footcandles can I expect to have gained from the counter tops and walls reflecting light from my T5s?

Thanks in advance.....I would appreciate your help.
Vicki

Becca · #2 01-22-2009, 09:30 PM

Hi Vicki! I hope someone answers your question soon as I would like to know as well. I have been looking at adding some mylar reflective film inbetween my light fixtures and on the side of the orchidariums.

HPS Chris · #3 01-23-2009, 12:45 AM

I would guess quite a bit. I do not use T5... but Any sort of extra reflection is a help... it is definitly hard to measure the light intensity with T5 or other flourescent bulbs as they're artificial lighting.

s1214215 · #4 01-23-2009, 09:28 AM

Hi

I cant see inside your light. Does it have individual reflectors? Individual parabolic reflectors fore each tube like the ones in this link are claimed to increase light being punched downward. I dont have a meter or I would test mine for you. These are the light reflectors I have and they clip to the light tube, so I can remove them. DE Lightings - T5 Accesories

I think good reflectors will do more for you than just lining with film. Marine "Reef Keeping" magazine often does articles on the benifits of good parabolic reflectors, and brand comparisons. So I guess theres something to that. Oh, and while single reflectors help, they are not as good as individual ones on each tube.

While lining may increase some light, it will be less. Anyone else care to chime in?

Magnus A · #5 01-23-2009, 09:28 AM

VERY hard to say . but it does not lovering the lightlevel so it can only be goog. It seams that you already have some reflector for your T5 so you only gain the stray light. Here in Europe we can by quite cheap light meters (US$ 30). They may not be accurate but atleast they can give an relative value of the before and after value.

Ross · #6 01-23-2009, 09:41 AM

Before and after readings are only way to tell for sure. The human eye is a poor light meter (it is so self-adjusting). My gut feeling is yes it will increase, but that style film is less reflecting than one would think. Hydroponics reflective mylar is the way to go. It won't so much increase the output as it does contain the illuminance - much like a HPS or MH fixture. Still not point source, though.

I have no problems getting accurate readings of my t5 fixtures with my meter. Not difficult at all. But without a solid reference point, it's very unlikely you will get an honest opinion to your question.

s1214215 · #7 01-23-2009, 11:46 AM

Hi

I agree with Ross. The type of reflective material will count and will contain light.

I have seen this matter discussed on marine fish forums before. Some people line the inside of light hoods and tank backs. From what I have read, individual reflectors will give a better result in directing the light down instead of allowing it to beam out randomly. An individual reflector is going to be way sharper than an single wide one over several tubes and both more effective than none or using just reflective film

I did a Google and founf this link that shows a drawing of how light refraction in a single reflector works. They do discuss films vs painting a surface white. I will try to find some better diagrams and some of refraction in a tank with no reflectors/single for comparison.

Light Intensity in an aquarium - Page 6 - Aquarium Plants - Barr Report

This thread from a fresh water fish forum looks like it goes for miles on the topic of lighting. I know this is all fish stuff, but I think a lot is relevent to lighting a case or growing space..

Brett

Ross · #8 01-23-2009, 02:26 PM

I also agree with Brett. I had ignored the single vs common reflector part because just about all high quality, high output t5 reflectors have individual compartments for each tube helping to controll light scatter. You still get some (unavoidable with t5s, but less than something like a shop light. The high quality german polished alum reflectors are just about the most effecient. Mylar will help control the light spred (so you might think of this as increasing foot-candles, but it is more correct to say there is less loss of foot-candles (not really an increase). I lined my indoor garden (which has an 8-tube 48" fixture.) Before the mylar I measured 3600 foot-candles at 11". After installing reflective mylar on three sides (I left the front open for fan ventilation) I now measure 3500 foot-candles, but I have been running the tubes for several months. I translate this as no increase in foot-candles, but the light being emitted is being conatined and not wasted.

VickiC · #9 01-23-2009, 10:46 PM

Hi,
I took a pic. of the underside of one of my t5s for you

I'm wondering if the reflectors that came on it when I bought it are the same as the ones you are talking about or not ??? If not, I should look into what you are speaking of. I'm guessing that I'm misunderstanding about the reflectors you are referring to, but maybe my husband can clear me up if that's the case. I do have a light meter, and it reads that a few footcandles reflect from the wall outwards and then a few also reflect from the bottom of the counter upwards (I don't recall exactly how many....I would need to measure again and make note of the amount). I do remember the amount wasn't much, but I figured every little bit would help (or hurt).....depending on the type of orchid I'm lighting. I don't know enough about lighting to determine how all this works together....the light from the T5s plus the additional footcandles that are reflected.

Thank you for your reply....I appreciate your help.
Vicki

Quote:

Originally Posted by s1214215

Hi
I cant see inside your light. Does it have individual reflectors? Individual parabolic reflectors fore each tube like the ones in this link are claimed to increase light being punched downward. I dont have a meter or I would test mine for you. These are the light reflectors I have and they clip to the light tube, so I can remove them. DE Lightings - T5 Accesories

I think good reflectors will do more for you than just lining with film. Marine "Reef Keeping" magazine often does articles on the benifits of good parabolic reflectors, and brand comparisons. So I guess theres something to that. Oh, and while single reflectors help, they are not as good as individual ones on each tube.

While lining may increase some light, it will be less. Anyone else care to chime in?

VickiC · #10 01-23-2009, 11:16 PM

Hi,
Oh.....I think I understand what you are saying.

As for the covering, the reason we didn't use Mylar is because we already had the aluminium foil insulation material you saw in the picture. It was left over from some insulating my husband had done to an add-on to his shop. Otherwise, I would have bought Mylar since you suggested it to me awhile back.

Your reply reminded me of another question that I meant to ask along with the one that I did. I was wondering how often I should replace my T5 bulbs- averaging 10 hrs. a day usage (more or less depending on the season, of course) Would you mind helping me with this one?

Thanks for your reply.....I always appreciate your help.
Vicki

Quote:

Originally Posted by Ross

I also agree with Brett. I had ignored the single vs common reflector part because just about all high quality, high output t5 reflectors have individual compartments for each tube helping to controll light scatter. You still get some (unavoidable with t5s, but less than something like a shop light. The high quality german polished alum reflectors are just about the most effecient. Mylar will help control the light spred (so you might think of this as increasing foot-candles, but it is more correct to say there is less loss of foot-candles (not really an increase). I lined my indoor garden (which has an 8-tube 48" fixture.) Before the mylar I measured 3600 foot-candles at 11". After installing reflective mylar on three sides (I left the front open for fan ventilation) I now measure 3500 foot-candles, but I have been running the tubes for several months. I translate this as no increase in foot-candles, but the light being emitted is being conatined and not wasted.