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derek_in_ontario

Need Advice on Flouresent lights to use.....

Derek_in_Ontario
19 years ago

Hello Everyone

I grow Phalaenopsis under flouresent lamps of 4 tubes per shelf. I have been using Sylvania Gro lux tubes, and my plants over the years have done well. My question is can they do better using something else? I have heard that some of the Philips lamps particularly the Daylight Deluxe are good. My tubes are up for replacement so I am interested in hearing your opinions, on any combinations I could be using here.... Thanks

Comments (32)

  • gawdly
    19 years ago

    I like my Philips Daylight Deluxe bulbs, and at $5 or less per 2 bulbs, you can't beat it. When I mentioned these bulbs earlier, Zink mentioned that these bulbs weren't the be-all end-all, but he said they were a really good design with a good phosphor mix suitable for plant growth.

    Sam

  • Derek_in_Ontario
    Original Author
    19 years ago

    They are cheaper that's for sure, I usually pay about 7.00 each for the Gro-lux. Do you use all Daylights, or do you mix them with something else? And are you growing orchids by chance under yours? Thanks Sam.... Derek

  • gawdly
    19 years ago

    I have mine mixed with Soft white bulbs. Yes, I am growing phals, paphs, and many onc. genera orchids under mine and in a case.

    Sam

  • gawdly
    19 years ago

    Are the Gro-lux bulbs discontinued? I don't see them listed on their website. THeir website also mentions Daylight bulbs, but I don't see any Compact or standard fluorescents in their product line.

    Kinda of disappointing.

    Sam

  • allotrope
    19 years ago

    Hey Sam,

    I contacted the distributor of the compact spirals that we talked about in a previous thread and since they didn't have any retailers yet (just wholesale) they agreed to sell me some by the case. So I have a few extra's for the moment. Not super cheap but 1/3 of what a local retailer was asking for his 5000k bulbs. I got some 55w 3500k and 6500k which produce a little less then 7,000 lumens (per pair) but will drop to 6,300 by 4,000 hours. I find them usefull for plants that are not in the "grow closet" ;-p

    I also finally found a local source for T5 High Output's. I ended up with GE's Starcoat 39w 3500k and 6500k tubes. The price is still a little steep ($85 CDN for a ballast/reflector!!!! and $15 per tube) but still much cheaper then what is found in petshops. They are producing around 7,000 lumens per pair but will stay at this level for most of its 20,000 hours.

  • gawdly
    19 years ago

    Hey there Allotrope!

    I've pretty much decided to purchase this light:

    http://www.abcbulbs.com/Item.asp?ID=SL85-65K&my_ID=23700&afid=

    And couple that with a 43W bulb that I have just laying around. I don't have any statistics on lumens output or whatnot, but it looks like a good bulb.

    At $30 or so delivered, it's not too bad I guess.

    Sam

  • gawdly
    19 years ago

    P.S.- THe lamp is rated for 3500 Lumens at 8000 hours. The Manufacturer is Sunlite, AKA- Sunshine Lighting Co.

    www.sunshinelighting.com

  • allotrope
    19 years ago

    Hi Sam, good find and decent price. I'm really impressed with 3500 lumens at 8000 hrs . Must be close to 4200 initial lumens. What is the life expectancy of the bulb, 8000 hrs? A similar bulb will cost over $60 CDN... ouch!

  • gawdly
    19 years ago

    Sorry, I think I said that wrong. I didn't get any initial lumens figures, just the stated output and the life of the bulb.

    Still sounds like a great light to me!

    Sam

  • Derek_in_Ontario
    Original Author
    19 years ago

    Hey Sam, the grow lux are still available here in Canada, so I don't know if maybe they are not where you are. I think I will give those daylights a shot. Not sure what to mix them with though, what do you think, warm white, or maybe mix them with new grow lux tubes?? Any particular warm white you could recommend?? Thanks Derek

  • gawdly
    19 years ago

    I'm using Philips Alto Daylight Deluxe and Philips Alto Cool Whites. Seem to be a winner of a combo, except I'd like it a bit brighter-so I'm switching over to compact fluorescents and a reflective light hood.

    Sam

  • sonnypippo
    19 years ago

    I am looking to set up a shelf lighting system and will probably go with Philips HomeLight Natural Sunshine 48" fluorescent (if I can find them). I was wondering if anyone is using these and how many bulbs I would need to generate 1000 - 3500 footcandles from distances of about 1 to 4 feet. Thanks.

  • watergal
    19 years ago

    I don't think you'll be able to generate 3500 footcandles at all with 48" tubes. About the best you can do is 750 to 1000 footcandles just inches below the center of the tubes, and that's with 2 shoplights for a total of 4 tubes. Perhaps a fixture with the bulbs RIGHT next to each other could do a bit better. But to get what you want, you really need to invest in a HID light. Sorry to be the bearer of bad news.

  • sonnypippo
    19 years ago

    watergal- thanks for the reply. perhaps absolute brightness is not the primary criteria i should be concerned about. from what i've been reading, PAR efficiency, red:blue ratio, and color temperature are probably more useful parameters to be looking at. basically, i am looking for an ideal set up to grow a variety of plants that require different light levels.

  • gawdly
    19 years ago

    Honestly, you can grow lots of things under weaker lights than nature-you just have to increase photoperiod. You know what I use and what I plan to transition to. I guess you can draw your own conclusions from that.

    In a few months I'll probably be able to offer up an opinion on the CFL bulbs I just purchased. They should be delivered to me in a week or so.

    Sam

    P.S.- I've got another orchid going into spike. My lighting seems to work pretty good despite the lower output.

  • allotrope
    19 years ago

    Hmm. I don't know about that watergal. I've been researching High Output T5's quite extensively and a single 48" 54w will produce 5,000 lumens which is equal to 5,000 foot/candles according to conversion tables. Trying to get 3500 footcandle at 4' distance might be difficult with fluoro's (but you could put some at the 2' level on each side).

    The advantage of the HID/MH/HPS is that they can penetrate "deeper" which is required for bushes/trees and they can provide the required lighting levels for larger coverage ie if you need to light a room. The disadavantage is the heat generated and the high electricity consumption.

    Fluorescents are great for shelf growing because they produce a lot less heat and therefore can be placed a lot closer to the plants. They use 1/3 less electricity to generate the same or higher light level (if you take into consideration the distance factor). I need to find someone with a light meter that can measure high light levels accurately across a range of wavelenghts in order to compare accurately. For now I am limited to comparing specifications provided by manufacturers.

    I've been using spiral compacts (43w warm 23w daylight) since June and I have rebloomed the following orchids: Zygo, Burrangea, Phal (spiking) and Paph under this setup. I also have 55w spiral (but only been using for a couple of weeks). The T5 HO (3' 39w) are also too new to see anything other then they are bloody bright.

  • watergal
    19 years ago

    I haven't researched the high output T5's. But I think that 5,000 lumens is more like 500 footcandles. Someone with more electrical knowledge please correct me if I'm mistaken.

  • sonnypippo
    19 years ago

    The difference between LUX and footcandles is a factor of ~10.76. LUMENS can not be directly converted into lux or footcandles, since it is only a measure of brightness as opposed to brightness over surface area.

  • allotrope
    19 years ago

    From http://www.theledlight.com/lumens.html
    "A LUMEN is a unit of measurement of light. It measures light much the same way. Remember, a foot-candle is how bright the light is one foot away from the source. A lumen is a way of measuring how much light gets to what you want to light! A LUMEN is equal to one foot-candle falling on one square foot of area.

    So, if we take your candle and ruler, lets place a book at the opposite end from the candle. We'd have a bit of a light up if we put the book right next to the candle, you know. If that book happens to be one foot by one foot, it's one square foot. Ok, got the math done there. Now, all the light falling on that book, one foot away from your candle equals bothÂÂ.1 foot candle AND one LUMEN!"

    I interpret this to mean that 1 foot candle = 1 lumen. Is this incorrect?

    From http://encarta.msn.com/encyclopedia_761579230_3/Light.html
    "The illumination at a different distance from a source can be calculated from the inverse square law: One lumen of flux spreads out over an area that increases as the square of the distance from the center of the source. This means that the light per square foot decreases as the inverse square of the distance from the source. For instance, if 1 square foot of a surface that is 1 foot away from a source has an illumination of 1 foot-candle, then 1 square foot of a surface that is 4 feet away will have an illumination of 1/16 foot-candle. This is because 4 feet away from the source, the 1 lumen of flux landing on 1 square foot has had to spread out over 16 square feet. In the metric system, the unit of luminous flux is also called the lumen, and the unit of illumination is defined in meters and is called the lux.

    Sonny, the Lux factor that you are refering to is for lumen per square meter not per square foot.

    The second statement is what I find interesting and I am puzzled why no one seem to include this in their calculation when talking about lighting. The HID/HPS/MH lamps produce more light per watt (see thread "Article comparing light source") but they have to be placed farther away because of heat. If we apply the inverse square rule mentioned above then it means that in order equal the illumination of a light source 1 foot away, your lamp has to produce 16x more light if it has to be placed 4 feet away. To me that means that a T5 HO which can be placed 12" from a surface without it overheating can be 1/16th as bright as the equivalent lamp to generate the same illumination. That means that I need to consume far less energy and the the same or better lighting.

    Your mileage may vary

  • sonnypippo
    19 years ago

    allo- take a look here:
    http://www.onlineconversion.com/illuminance.htm

    lux and footcandles can be intercoverted, but lumens can not. only lumens over a given surface area measurement (e.g. m2, cm2, ft2) can be converted into other illuminance units. lumens can be used to calculate illuminance (lux or footcandles) if the surface area is known.

    from the link you posted before:
    http://article.dphnet.com/cat-04/lightcompare.shtml#S-2

    Another quantity often quoted when talking about light output is lux. Lux is a measure of illumination, not flux. Flux refers to the light energy that leaves the source. Illumination refers to the light energy that reaches the receiving surface. Lux is equivalent to lumens/m2. Lux cannot be computed only from the known data of a light source. Additional information regarding the illumination geometry, reflectors, distances, intervening media (glass covers, water) must be taken into account.

  • allotrope
    19 years ago

    All the conversion sites say that you can't convert directly lumen to foot candle but the definition of a lumen is "all the light hitting a 1 square foot area from a candle placed 1 foot away". To me that means that 1 lumen is 1 candle light over 1 square foot. So as long as we are comparing a square foot area at 1 foot distance 1 lumen=1 foot candle. Those just happen to be the conditions that the lights are measured for lumen rating of the bulbs. That is why I say that 5000 lumens light bulb = 5000 foot candle. You can place a fluorescent 1' away from a plant but not with a lamp.

    Illumination geometry is where the lamps have superior results over fluorescents (better at lighting wider areas compared to fluorescents). You can get the geometry analysis of lights from some manufacturers but I can't make heads or tail out of the numbers... yet.

  • sonnypippo
    19 years ago

    allo- i can tell you this much... if i hold the light meter right up against the 42W 4100K bulb, i will get readings of 15000 - 20000 footcandles. at 6" away, i read about 1200 footcandles.

  • allotrope
    19 years ago

    If we use the inverse square law, you should be measuring over 3500 lumens at 6" if the 15,000 lumens is correct (1 x (1/(0.5 square). What is the reading at 12"? When you measure, do you point the unit at the light or at a 12x12 white paper that was 6" away (Iike in photography)?

    I would have expected to see 1800-2100 lumens at 12" for a 42w 3000k bulb. I would expect a lower lumen rating for a 4100k bulb but that is a very big difference. Do you know what it's initial avg rating supposed to be for your bulb?

  • sonnypippo
    19 years ago

    i think the reason for the exponential decrease in footcandles with increasing distance is that light is being dispersed in three dimensions, while you are only measuring for two (i.e. on a flat surface). the light meter uses a small disc which i face in the direction of the bulb. the bulb is rated at 2800 lumens.

  • allotrope
    19 years ago

    I can't wait to do some tests when I get back. I'm really intrigued with all these claims from the manufacturers. If they claim 2800 lumens but you can only get 1200 at 6" then something is very wrong.

  • gawdly
    19 years ago

    Hey, I hooked up those CFL bulbs last night. Wow! that is some bright errr, stuff. I think my plants will be very happy with me for it.

    Just thought I'd let everyone know that the Sunlight bulbs are the bomb.

    Sam

  • Alexandra7
    18 years ago

    Guys, I was reading a post where you two had a very interesting conversation about lumens and footcandles. I found this link and thought it would help to sort this out.

    Allotrope...I am not sure if you have had time to conduct your experiments.

    Sonny...it looks more like what you were saying in regards to footcandles dropping over space. Lumens will stay the same...but the footcandles will diminish.

    Here is a link that might be useful: The Led Light

  • maineman
    18 years ago

    Sonnypippo,

    "...if I hold the light meter right up against the 42W 4100K bulb, I will get readings of 15000 - 20000 footcandles. At 6" away, I read about 1200 footcandles."

    I think there may be something wrong with your light meter. What sort of readings do you get for full sun outside?

    MM

  • shrubs_n_bulbs
    18 years ago

    Sonnypippo's numbers sound about right to me, for a 42W compact fluorescent. They are compact (duh!!) light sources and are very intense right at the bulb. 1200fc at 6" sounds about right, maybe a little high but not far wrong. Depends on the bulb shape (CFLs tend to be fairly directional sending the light out "sideways", although the spiral shapes send more out the "end") and what sort of reflector enclosure there is.

  • maineman
    18 years ago

    Shrubs_n_bulbs,

    "Sonnypippo's numbers sound about right to me, for a 42W compact fluorescent."

    Well then, they are very bright. As I recall, full daylight ranges between 5000 foot candles and 8000 foot candles. My overdriven cool white T8s deliver about 500 foot candles to the plant leaves.

    MM

  • shrubs_n_bulbs
    18 years ago

    My overdriven cool white T8s deliver about 500 foot candles to the plant leaves Then try putting them closer :) You can get several thousand foot-candles at the surface of a regular T8, so maybe 10,000fc right on an overdriven one. Of course that drops rapidly as you move the tubes higher, but you should be able to get 500fc at about a foot.

    Typical lumens from a 42W compact fluorescent is 3,200. If the bulb is 2" across and 4" long then it would have about 30,000fc at the surface.

  • maineman
    18 years ago

    Shrubs_n_bulbs,

    "My overdriven cool white T8s deliver about 500 foot candles to the plant leaves. Then try putting them closer :) You can get several thousand foot-candles at the surface of a regular T8, so maybe 10,000fc is right on an overdriven one."

    My plants are fairly close to the bulbs now and the faster growing ones can cut that distance to nothing in two or three days and scorch their leaves. On several occasions in the last few weeks they have done that.

    I am rather new at this illumination calculation stuff, but lets try to "do the math" on the basis that one foot candle is one lumen per square foot. I'll do the calculations a step at a time so that you and others can check my work.

    My T8 bulbs are nominally 48 inches long and one inch in diameter. However, the actual light emitting length of the bulb is a little less than 48 inches, about 46½ inches. We can calculate the area of the emitting phosphor as the product of the circumference of the bulb times the length of the bulb. Since the circumference is pi times the diameter, 3.14159/12 = 0.261799167 feet times the length of 3.875 feet is about 1.01447 square feet. That's pretty close to one square foot of emitting area per T8 bulb, so for simplicity let's use that one square foot figure.

    Hence the foot candle intensity at the T8 bulb surface is, numerically, simply the lumens output of the bulb, to within a percent or two. My Philips Universal T8 TL741 Cool bulbs are rated at 2850 lumens, so that would be the maximum foot candle measurement right at the phosphor.

    Since overdriven bulbs put out about 50% more lumens, that would be 4275 lumens overdriven, so you couldn't expect a legitimate measurement of more than 4275 foot candles from one of my T8 bulbs, even when measured at the surface. That drops off rapidly as you move away from the surface.

    MM

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