Buying Grow light fixtures.

beholderOctober 25, 2006

Hello, my name is Shawn and am an avid plants man of 10+ yrs.. I was wondering if you would be able to help me narrow down my options for a grow-light fixture. I have read several comments regarding the different lights and the photon efficacy of phosphorescent coatings and what not. I believe I have gained a new respect for an elementary-physics indoor lighting point of view to growing empowerment. I am a seasoned grower of all things in and above the soil. After several years, I am now wanting to enjoy gardening indoors again. I would be setting up a 4'X 4' in-home area for mature full-sun blooming plants. For cold-season growing mainly with a propagation, "fragile-plant", and terrarium setup year-round. I have used a 400W MH in the past but am looking at possibly a dual-spectrum 500W HPS/MH unit for around $350.00. I have also considered a T5 6500K/3000K 4'/8 bulb unit for $265.00. I am leaning toward the T5 unit because of the "safer" heat-spread. Also tempting is the new "Blue" HPS bulbs though and possibility of only needing to have a single 400W+ HPS "Blue" hortilux (or similar) bulb for around $250.00 +/-. might be more efficient in getting the photons the plants really need to thrive, lush green and capable of bloom. If the HPS + or Dual-Spectrum units are the way to go, rather than the T5 "6500K/3000K" 4'/8 bulb fluorescent, are the new digital ballasts the best efficiency, also considering bulb-life? I am just curious as to what you would buy if you had the extra-cash just for grow-light fixtures. Let me know what the best bang for the buck would be in your consideration. I respect your point-of view as a fellow plants man and hope for nothing less. Thank you. - Shawn

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Reasonably Priced Units for general-purpose indoor growing.
I can have a 500 Watt Dual MH/HPS built by request by sunlight supply.
Of course there are the single bulb units as well. My main concern is whether or not the 8 bulb T5 units really up to PAR with the capabilities afforded by todays HPS/MH grow-bulbs? The T5's do seem more efficient in many ways over HPS/MH and seem safer to maintain. And as we can see, the prices are very affordable for a high-quality product. What are your thoughts? This seems to be the best market for plant productivity. - Shawn

    Bookmark   October 25, 2006 at 10:31PM
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As an incentive to prospective reply's I have some wonderful information on how UV light influences some key aspects of plant growth and also insect life in a controlled environment. Let me know if you would be interested to have this info! - Shawn

    Bookmark   October 26, 2006 at 4:50AM
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shrubs_n_bulbs(z8/9 UK)

Info is always interesting ;)

Definitely go for a digital ballast, whatever you decide. T5 ballast will be "digital" anyway. The HID digital ballasts are better for the bulbs, better light output, and use less electricity, what's not to like :) Quieter and cooler too!

I think an 8 lamp T5 unit will cost you more up front unless you build your own. Bit of a ripoff really since the most important component, the ballast, can be sourced at under $50 for a quad 54W. And almost identical ballasts for T8 tubes are more like $10! Of course you are also paying for eight reflectors and a whole shipload of wiring. And shop around for the tubes, aquarium places will charge you $15+ but you can find them for less than $5 in a regular lighting store. T5 fluorescents have the advantages of long life, good spread of light and heat, and very good lumen maintenance.

If you can fit them in the space, consider using 12-14 good quality triphosphor T8 tubes on a high frequency ballast to get the same light output, the same spectrum, and the same efficiency, but at a much lower cost. This is what I use because I have a relatively small system with a mangeable number of tubes and can get the light intensity I need from T8s. Definitely the cheapest solution today, the only drawback is you need a bigger area to get the same amount of light as with T5s, and a much bigger area than HID, so no good for very high light intensities.

Modern HID lamps have improved greatly but still don't offer the same lumen maintenance or lifetime as the fluorescents. But if you need a high power system and you want to include HPS in there, then you will be getting a good chunk more light for your wattage. I don't rate the Hortilux Blue bulb, too much loss of efficiency and lifetime to produce more blue light than you want. Look at ceramic metal halide bulbs if you feel the need for full spectrum.

BTW, that spectrum on the Sunblaze page is extremely deceptive. T5 lamps don't produce a spectrum anything like that, they are standard triphosphor fluorescents and have a fairly peaky spectrum with a high proportion of the light concentrated in narrow bands in the blue, green, and red. There is a lower level fairly continuous spectrum and it appears that Sunblaze have "reproduced" their spectrum in such a way that the narrow peaks are not visible, just a seemingly continuous spectrum. Combining the 6500K and 3000K tubes is also a piece of meaningless rubbish. Since both colours have their three peaks in exactly the same place, there is no "full spectrum effect", you merely get what you would have got from a 4100K tube. Nothing wrong with the mix, just nothing special about it either.

    Bookmark   October 26, 2006 at 12:19PM
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Here is the follow-up to a question on an 8 bulb T5 unit.
What is the growing area for the Sunleaves Pioneer IV T5 Fluorescent Grow Light Fixture? It says a larger area but what is the approximate footage? 4'X4' or 4'X2'? Thank you. - Shawn
Good question, the answer actually depends on the use.
If you are fruiting and flowering I would keep no more plants than what will fit directly under the light from a distance of four inches above.
This is for plants like tomatoes, peppers etc.

If you are growing salad greens, spinach or herbs the light demand is significantly less so the light can be raised thus increasing the overall growing area.

In short I would say for fruiting and flowering the area is 2x4. For vegetative growth the area is 4x4, this is of course for maximum results. Technically you could take one of these lights and flower or fruit your plants in a 6x6 area but the overall finished plants would be leggy and not quite what I think you are looking for.


Jeff Lancaster
Sunleaves Garden Products
Hmm. I imagine then I would have the exact same effect with MH/HPS fixture. It is due to the obvious exponential light diffusion from source to target again.
BTW- Thanks shrubs_n_bulbs for the timely response! As long as either 8-16 T5/T8 tubes can put out an equal high-intensity plant sensitive wavelength as the dual MH/HPS bulbs of same wattage, then that would really make me want to opt for the T5/T8 arena. I have grown under MH before and the whole narrow point source freaked me out. I have a bit of OCD so it might be more assuring to know my photon generating source is more dispersed. Again, as long as the dispersion of the source does not mean greater diffusion of light the further away from the plant. I assume the concept is similar to the 400 Watt HID bulb being 8-16 T5/T8's in one point source. If so wouldn't spreading out the point of light on an HID bulb, in theory, mean weakening the # of photons it puts out per m2? And if this is just what a High output Fluorescent setup does then wouldn't getting closer to the plant also narrow the field of light to just a few bulbs rather than the whole set of bulbs to one plant? So that would mean there would have to be an in between area of optimal light spread to each plant under the light right? Whereas under an HID bulb the source of light is so small that the strength of photon production does not diminish as readily. Sort of like cooking with a heating mat v.s. a bunson burner right?
If I am correct it makes me wonder about the material shown on the following web page: .
Sure he is comparing a generic 400 W MH but is the discarge of photons really weakened to 20,000 Lum. from variables? It seems those in-efficient variables are no longer as such. I might want to go with an HPS/MH dual setup after-all if mulitipled intense Fluorescents will not broadcast the same photons per m2 as can be acheived with HID bulbs at the same distance, to a point. I would imagine the effect would be like focusing the beam of a floodlight or even focusing the light through the lens of the human eye. It is all about getting the right photons, at a precise intensity to acheive verifiable results. Have I made my mind up yet as to what to build? No, but I am getting closer. 2 Bloomwright Uiversal Socket Assemblys with a dual hood and digital ballast might be the way to go if T5/T8 doesn't suit my needs. I wish I could find out if my plants will be lush and green and in bloom under either without buying both. That is why I am getting this info. I have spent too much already on uneducated decisions. My real dilema is that my plants will be sitting under the grow-light from different heights but with similar needs. I will try to get them as close up to the source as possible but will the strength of the photon signal be as strong from the multiple T5/T8's as the 400 Watt HPS/MH when focused at just the right equal light-spread distance? Good questions but it is a real job in finding the answer. Thanks again. - Shawn

    Bookmark   October 26, 2006 at 7:42PM
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Thank you for your keen insight on the lights. Now, I have posed a new set of questions to my post. I always thought the Kelvin degree measure on Flourescents was silly. The industry really needs to serve horticulturalists better by using the more applicable Photosynthetically Active Radiation (PAR) system. It makes much more sense and is easy to learn. It helps us humans understand plant sight a little better, not excluding non-photosynthetic light such as some of the UV.
Here is the information I foretold of. I have found the one and only Hydroponic sales shop where I live and they gave me about 20 free magazines on indoor gardening monthly articles. I can see through most of the marketing politics if I stick to just the scientific stuff, which there is a good amount of.
I was going to OCR scan each page for you but I found the online version of the magazines. I will try to point you to what articles I am currently reading and find of interest.
Maximum Yield's Indoor Gardening Mag.:
An interesting chart article on HID intensity for gaining optimal crop yeilds.
Growing Edge Mag.:
Here is the neat article on UV light in relation to aspects of plant tissue response and insects.
http://www. /magazine/current_issue/view_article.php3?AID=180134
The indoorgardener mag. is another convoluted construed publication but there is some info. worthy of argument at times. No online mag. unfortunately but I will put a short OCR text article on a humorous experiment growing under MH and T5's. This is just for reference, do what you wish with that one as there is no growing info on the page of any use.
Okay, so I have just started reading the magazines I do have and am sharing them with another friend too. But I know you and others can find just as amazing stuff in the online text only versions as well. Plus you don't have to deal with the ads on every other page.
I know there is a lot of hype in these ad. mags but right now they are my only ready source for some good info on indoor gardening. I am against the need to use manufactures brand names as anyone, but I am assuming that is how a meritocracy works. Thanks again. - Shawn

    Bookmark   October 26, 2006 at 8:26PM
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Indoor garden volume2 issue1 pg. 48
The Satellite Fluorescent Light II Test
By Charles Winslow
It appears that in a side-by-side trial, the Satellite II fluorescent light surpasses metal halide lights.
In a three-month, side-by-side test, habanero pepper plants growing under a 210-watt Sunleaves Satellite II fixture exhibited healthier, more compact growth than habaro peppers grown under a standard 400-watt metal halide lamp. Aside from the spacing and the type of light offered, the growing conditions of the pepper plants were identical: hydroponic system, type and amount of nutrients, substrate and light cycle duration.
All plants were grown in continuous aeration hydroponic systems. In each system, a submersible pump suctioned to the bottom of the nutrient reservoir continually splashed Technaflora's Recipe for Success vegetative growth formula onto the roots. The pepper plants were started in horticultural grow plugs and then placed in plastic net cups containing expanded clay pellets.
With regard to light intensity, the Satellite II, equipped with two full-spectrums TT-105 fluorescent "grow" bulbs, emitted a total of 21,000 lumens and the metal halide lamp put out 30,000 lumens. The pepper plants were positioned as near each light as possible without scorching  46 centimetres from the metal halide lamp and 10 centimetres from the fluorescent fixture. Despite the marked difference in total lumen output, light meter readings taken at the plant canopy level registered higher for plants growing under the Satellite II. Plants received 18 hours of light daily."
I have the pics on the pdf article. They called this article "Para Lumen Paradigm Shift" on the cover. If it is a shift in thinking it certainly hasn't come full-swing just yet. Enjoy! - Shawn

    Bookmark   October 26, 2006 at 10:05PM
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shrubs_n_bulbs(z8/9 UK)

The Prolighting article illustrates the vast amount of utter cr@p that is written by people trying to sell fluorescent hi-bay lighting. For simplicity I would suggest you ignore such comparisons as they are utterly skewed to the point of being lies. Modern fluorescents (T5, T8, or suitable T12) now have efficiencies virtually as high as modern high power metal halides, and the lumen maintenance is somewhat better, although not to the extent indicated in such comparisons which use obsolete technology. There just isn't a compelling difference in efficiencies (it is a given that obsolete technology fluorescent or metal halide is significantly less efficienct and hence more expensive in the long run), and decisions need to be made on the basis of convenience, retro-fitting costs, and usage aspects like dimming and occupancy switching. For us plant freaks there is also the question of spectrum. And such comparisons generally ignore HPS which is still significantly the most efficient lighting for growing.

Your more general question about light intensity falloff with distance is a very complicated one and has led to much confusion and more cr&p being written, even by people with great experience of growing under lights. The oft-quoted "inverse square law" or the "exponential" light dropoff is simply irrelevant except for a point source without a reflector. Also, much confusion has been caused by the inherent ability of a bright light source used at a distance to provide light which drops off slowly with distance, a factor which has nothing to do with the nature of the light source itself merely with its total light output. Any reflector focuses the light to a certain extent and the intensity drops off more slowly. Fluorescent tubes do not obey these laws even without a reflector because they are extended light sources. The light intensity from a fluorescent, or an array of fluorescent tubes, drops off more slowly than from a point source like a metal halide. But note this doesn't mean you get higher intensities from the fluorescent, in fact just the opposite. The intensities at a large distance from a fluorescent array or single HID giving out the same total light are the same, but as you get closer to the HID the intensity rises more quickly. It can be hard to think about and perhaps isn't necessary. The crucial aspects are the total light output and whether you can get that light fairly evenly onto your plants and only onto your plants.

The only thing of relevance I see from the comparison article is "light meter readings taken at the plant canopy level registered higher for plants growing under the Satellite II". This is crucial! Whatever the lumen output of the various tubes, if that output is not reaching the plants then it is a waste of time. Therefore the comparison is virtually meaningless. Place the metal halide closer and use a fan if scorching is an issue, or water the plants properly. It would be interesting to know the light intensity nearer the base of the plants, particularly as they reach the fruiting stage. Another critical metric would be total yield, either vegetative or fruit. Again, you have to think about the practical considerations of getting an even spread of light over a wide area and I like long tube fluorescents for this, but a solid alternative is a well-enclosed white growing area. The distributed nature of multiple fluorescent tubes also allows creative solutions like arranging the tubes around the sides of the growing area instead of simply above.

Just as a matter of interest, the Satellite fluorescents are actually compact fluorescents, effectively an 8' T5 (I think) fluorescent bent in half. 105W and a claimed 10,000 or 10,500 lumens, they aren't clear which. Very expensive, you get identical output and efficiency at lower cost from two 54W T5 straight tubes, although they need slightly more room. Again almost identical output and efficiency and much lower cost from 3x36W T8 straight tubes (36W T8s not common in America, you would have to drop to 32W or look for true 40W tubes), obviously needing more space again. We are in a wonderful position as growers of being able to choose exactly how much light intensity we use, all the way from off-the-shelf $2 T8s, through straight T5s and high-power compact fluorescents, to HID lamps bright enough to burn foliage. The trick is to ignore all the competing advertising claims about which is "best", because none of them are best, they just achieve different things at different costs.

Here is a link that might be useful: Satellite II Comparison Test

    Bookmark   October 27, 2006 at 10:53AM
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Thank you again shrubs_n_bulbs! You are amazing! I am so glad there are those whom are like minded that I can discuss and gain insight into the minutiae of growing plantlife. It is so exciting being able to take plant growth to a scientific level, and anything else for that matter. But I really do enjoy being around plantlife the most. It is wonderful to me and envigorating. I have made the decision, because my passiflora cuttings require it, to build my own T8/T5 setup for the maturation stages of my cuttings and to buy a 400W ceramic MH with a dual hood for a 400W HPS in the future with my T8/T5's for vertical supplemental side lights in the grow-room. Thanks again! Wish we could visit in person. Lots of Love. - Shawn

    Bookmark   October 27, 2006 at 6:49PM
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I am going to post a new subject called "Grow light info. board". Where you and I can post any cool info. we can find,on the internet, through scanned magazines, video, or radio, on the subject of the growing arena of plant-light physics! Lots of love.- Shawn

    Bookmark   October 27, 2006 at 6:53PM
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If you could only get one unit, either a 400 Watt High-output HPS with a digital switchable ballast w/reflector or a T5 8 bulb 40,000 Lumen unit, which would you choose? I have to decide and am having a really hard time now. Both units are the same price. Again it would be for all stages of plant growth. Help!
BTW- Do you know where the equal Lumen output and distance from the top of the leaf that an HID bulb and an equal T5/T8 unit would be with specs.? Thank you. - Shawn

    Bookmark   October 31, 2006 at 4:05AM
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shrubs_n_bulbs(z8/9 UK)

If you could only get one unit, either a 400 Watt High-output HPS with a digital switchable ballast w/reflector or a T5 8 bulb 40,000 Lumen unit, which would you choose?

I think that depends on the plant. I grow cacti and succulents and they appreciate relatively high levels of blue and near UV light, so HPS isn't a good choice. But it also depends on location. As a supplement to natural light, HPS is excellent since the natural light supplies those parts of the spectrum that are missing from HPS light. An arrangement often used by commercial growers (and they are worth listening to because they have real money riding on their choices) is primarily HPS with supplemental blue light for some stages of growth.

Do you know where the equal Lumen output and distance from the top of the leaf that an HID bulb and an equal T5/T8 unit would be with specs.?

Impossible to say, it depends completely on the reflector arrangements, number of tubes/bulbs, spacings, etc. Also, intensity at the top leaf is not the only relevant measure. A more distant light source will provide for a light intensity that drops less between the top of a plant and the bottom, and this may prove to be a better choice for tall plants than one that provides higher intensity at the top leaf but much less at the bottom leaves. For example, a fluorescent tube 1" from the top leaves may provide very high light intensity to those top leaves, but provided a tenth or less of the light intensity at the bottom of the plant only a few inches lower.

    Bookmark   October 31, 2006 at 8:52AM
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