My sister and her friends actually rolled up one of those Big Bambu papers but it didn't burn very well.

Actual draw; LED watts don't mean much since there is so much variance. I wouldn't even bother with the 1w diode lights...

A truly classic album and album jacket.

Oh, almost forgot: at what cubic foot of indoor grow area do you begin to run into diminishing returns versus HID setups?

Thanks again!

I'm not sure if I understand the question? Are you asking which light (HID vs LED) is most cost effective?

SisterMaryElephant wrote:
Mother Nature is often a limiting factor. You *can* beat the Sun, except when it comes to price. Plasma lights have potential but I'm not switching to plasma yet.

There is a theory, that we've talked about on the forums, that suggests that the IR spectrum may be why LED lights lack the yield that HID lights can produce. Some have suggested that raising the ambient temps may help LED lights yield better since most of the LED lights lack the IR spectrum.

The point still stands; you can't expect top-shelf results by skimping on light and not enough w/sqft is skimping. Suggesting that small light (300w) will properly cover a large space (4x4) is skimping (18.75w/sqft) and not based on real world grow results. CLW suggests 40w/sqft for flowering with their 5w diode LED lights and I'd suggest that even that is exaggerating a bit if you want top-shelf results. You'll certainly do better with 40 than 20 or 30 but even with higher numbers HPS is still king...for now. I've yet to see any LED grow that beats top HID grows.

I'd love to be proven wrong though...

Is infared a factor? My understanding is that infared waves (not near infared waves) cannot pass through glass instead it is absorbed, hence probably part of the reason why HID bulbs heat up so much.

Is the amount of light output the determining factor? Afterall 95% of photosynthesis is supposedly faciltated by Red and blue light, so as these lamps are producing light in this range but still failing to keep up with HID lamps specifically HPS lamps (which prooduce a good chunk of their light yellow and green as well as red) one has to ask what is really going on.

Watts mean nothing to a plant, spectral output and intensity of light on the other hand do and this is what needs to be considered, for instance I used to run philips 840 TL-D reflex tubes and for my 288w worth of tubes I was able to yield around the same amount as my Hps 600 HID lamp needless to say I soon got rid of it

(Welcome to the forums!)

I believe that leaded glass will block UV and IR but most bulbs and hood glass should be lead-free. I think the plasma inside the bulb creating IR is why it heats up.

Good question. The amount/intensity of light certainly affects growth but how that light is measured can skew the numbers one way or another. This is why I dismiss PAR as a meaningful measurement. I'm not sure about that 95% number either but that's not important right now.

There are clearly multiple factors for grow lights; spectra, intensity, coverage, heat management, cost, etc. Many growers use grams per watt to compare efficiencies. We've found that more watts per square foots usually results in more yield and better density. UVB seems to stimulate trichome growth. Really there are pros and cons with virtually every growing decision we make and you have to take into consideration other factors like environment, genetics, experience and grow styles when deciding on lighting choices.

SisterMaryElephant wrote:(Welcome to the forums!)

I believe that leaded glass will block UV and IR but most bulbs and hood glass should be lead-free. I think the plasma inside the bulb creating IR is why it heats up.

Good question. The amount/intensity of light certainly affects growth but how that light is measured can skew the numbers one way or another. This is why I dismiss PAR as a meaningful measurement. I'm not sure about that 95% number either but that's not important right now.

There are clearly multiple factors for grow lights; spectra, intensity, coverage, heat management, cost, etc. Many growers use grams per watt to compare efficiencies. We've found that more watts per square foots usually results in more yield and better density. UVB seems to stimulate trichome growth. Really there are pros and cons with virtually every growing decision we make and you have to take into consideration other factors like environment, genetics, experience and grow styles when deciding on lighting choices.

Hello SME, thanks for welcoming me aboard appreciate it

I have to respectfully disagree with you with regards to glass (silicon) any radiation approximately below 300nm or above roughly 700nm is blocked by lead free types of glass, as a test hold a glass in front of a motion detector and watch as the signal is absorbed and no longer passes through the glass. Electromagnetism and matter can react with each other in a few different ways one way is vibrational the other is electronically.Through vibrational interactions with light, glass can block IR 700nm upwards. Through electronic interactions with light, glass can block UV 300nm downwards.

When you next buy a Hps bulb check the spectral output of the graph on the side of the packet, I am willing to bet there are no emissions in the IR range, so I do not consider IR to be a contributory factor with regards to the indoor scene as no lights or insignificantly few are outputing within this range. Its not to say that IR is not a factor on the whole though.

I agree with you to an extent with regards to how ther term PAR is bandied about within this industry, I think the term PAR can be skewed and used as a marketing ploy but its not to say PAR has no value this I feel is incorrect, by the very definiton of the acronym "Photosynthetically action response" if you were actually designing a lamp that catered to PAR this would in fact be a great thing, problem is when lazy ignorant conmen and women decide to build growlights without understanding the fundamentals then apply the term PAR to their shite products excuse my french

Again I agree with you there are definitely multiple factors as you have outlined above, but the thing is I have had a play myself for many years and I have run side by side tests in 1m2 areas where everything is equal except using different lights and I have found that the fluorescent setup at just over half the power of a HID set up always produces a similar yield.

My conclusion as to why is happening is this light diminishes by the square (inverse square law) so on the one hand I have to hang my 600w watt a foot or so above my plants so my 90,000 lumens now becomes 22,500 lumens at the canopy, on the otherhand my fluorescents are cool to the touch so I can literally place them an inch above the canopy meaning I do not get hit by the inverse square law, meaning I am delivering 26,800lumens to the canopy, plus the fact the tubes are longer and evenly spaced apart it means I get an even distribution of light, this is why I feel running at half power I am able to compete with something double the power and it seems to be backed up mathematically as to why this is so.

I think the majority of people get confused on certain issues they will say Fluoresents are no good for flowering as they are weak etc, but as I have explained above applied correctly they are actually better due to the heat limitation of the HID, light is light regardless of where it comes from e.g HID light is not superior to Flourescent light it is the same light albeit slightly different manfacturing spectrums,

So its about looking at the specific pro's and cons of each technology and seeing which is best suited. And this is where I have a slight issue with Led's by design they are narrow beams of light akin to lasers so due to this fact they to have to be hung some distance above a canopy, so now they are also getting hit by the inverse square law which is not good regards to energy efficiency as you have a incurred a loss because of the distance also the coverage versus the power used is not great either, having dabbled with them and built my own I still feel for now fluorescents are superior to both HID's and LED's.

You don't have to agree but the makers of the EYE Hortilux HID lamps have charts showing output above 700nm, even over 740nm on the MH and HPS bulbs so the lead-free glass isn't blocking it as much as you thought. Also UV is 100-400nm, it's just the UVB that's close to 300 and HID specras range under 400 too.

HID certainly outputs less IR and UVB than it does white/red/blue but that doesn't mean it's not used by our plants and...maybe...that could be *partly* why LED grow lights aren't keeping up with even equal powered large HID grow lights. Higher powered diodes that will surely show up eventually might allow LED to take the crown as king of the grow lights but that's not today.

Since this is a grow light forum and we're talking about comparing grow lights, I still say PAR is more marketing hype than useful measurement. The one with the higher PAR isn't always the better grow light and that's a problem since that's how many manufacturers make the claims/implications that their lowered powered LED lights will outgrow higher powered HID lights. Results don't back up the claims, at least not with cannabis growers.

The inverse square law can't be ignored but there's still no way that that less than 300w of fluorescents will outgrow 600w of HID unless you're doing something wrong on the HID side. You can't cut half of the power and expect equal results, that's where the LED claims are failing too. You can't compare flower quality/density, imho, either. HID is superior in terms of intensity and that's a big enough difference. Can people grow with fluorescents? Of course, they can grow with incandescents too...if they wanted, but there are better lights available. Sorry but fluorescents are near the bottom of the barrel for me. I wouldn't use them for more than rooting clones or starting seeds but people are free to use what they want.

LED lights can have varied diode beam angles, they're not always pinpoint focused. LED and HID light *can* be kept closer than 1 foot but as we know, the closer to the canopy, the less area it will cover too. Higher powered, more intense, lighting can also bleach the tops of plants. LED manufacturers "stretch" the coverage by suggesting higher placements than could be achieved. Also partly based on the assumption that they can use less watts/sqft because of the tuned spectra.

SisterMaryElephant wrote:You don't have to agree but the makers of the EYE Hortilux HID lamps have charts showing output above 700nm, even over 740nm on the MH and HPS bulbs so the lead-free glass isn't blocking it as much as you thought. Also UV is 100-400nm, it's just the UVB that's close to 300 and HID specras range under 400 too.

Hello Sister you will have to excuse some of my knowledge might not be up to date as I rarely frequent grow shops nowadays, but when I used to the bulbs from the major players did not emit anything in the infared range and from what you have said here I still stand by that claim. For clarity 700nm to approximately 1400nm is considered by definition "near" (not actually) infared, anything beyond this point it is then considered shortwave IR 1400-3000nm, Midwave IR 3000-8000nm, Longwave IR 8000nm-15,000nm and finally Far IR 15,000 upwards.

SisterMaryElephant wrote:HID certainly outputs less IR and UVB than it does white/red/blue but that doesn't mean it's not used by our plants and...maybe...that could be *partly* why LED grow lights aren't keeping up with even equal powered large HID grow lights. Higher powered diodes that will surely show up eventually might allow LED to take the crown as king of the grow lights but that's not today.

I think here you mean Near infared And I never claimed that near IR and UVB wasn't used by plants quite the contrary I think they are beneficial

SisterMaryElephant wrote:Since this is a grow light forum and we're talking about comparing grow lights, I still say PAR is more marketing hype than useful measurement. The one with the higher PAR isn't always the better grow light and that's a problem since that's how many manufacturers make the claims/implications that their lowered powered LED lights will outgrow higher powered HID lights. Results don't back up the claims, at least not with cannabis growers.

The term PAR has definitely been abused and skewed but its not to say that it does not have merit if properly explained. Certain wavelengths are of higher value to plants than others so if they were assigned values then this would help a lot, the only problem I see is that from species to species there will be variations in PAR values, but I say at least its better than lumens which is based upon human eye response.

SisterMaryElephant wrote: The inverse square law can't be ignored but there's still no way that that less than 300w of fluorescents will outgrow 600w of HID unless you're doing something wrong on the HID side. You can't cut half of the power and expect equal results, that's where the LED claims are failing too. You can't compare flower quality/density, imho, either. HID is superior in terms of intensity and that's a big enough difference. Can people grow with fluorescents? Of course, they can grow with incandescents too...if they wanted, but there are better lights available. Sorry but fluorescents are near the bottom of the barrel for me. I wouldn't use them for more than rooting clones or starting seeds but people are free to use what they want.

To be honest I am a bit dumbfounded by your response here, on the one hand you fully acknowledge the inverse square law then on the other hand you dismiss my claims as "unless you're doing something wrong on the HID side" I have been growing for near on 2 decades, these were controlled experiments where everything was equal except of course the lights so no I did not do anything wrong on the HID side. As I have clearly shown actual light to the canopy was higher due to the fluorescents being able to be place so close, its this type of igorance as to what is actually going on even when its explained that makes me sigh , curious to know have you ever run your own side by side trials?

SisterMaryElephant wrote: LED lights can have varied diode beam angles, they're not always pinpoint focused. LED and HID light *can* be kept closer than 1 foot but as we know, the closer to the canopy, the less area it will cover too. Higher powered, more intense, lighting can also bleach the tops of plants. LED manufacturers "stretch" the coverage by suggesting higher placements than could be achieved. Also partly based on the assumption that they can use less watts/sqft because of the tuned spectra.

I know Led's have varied beam angles having built a few.The problem I found when building them a while ago (things were at the 3w stage), so if you used 120 lenses you sacrificed intensity, 60's were to narrow, I found 90's to be the happy medium but coverage was far from great and my fluorescent rigs were still superior. Having not built a 5w led rig I cannot personally comment on them, but from what I have read here I still see there are a lot of limitations. Although its not to say that things won't move on as I am sure they will

I'll skip around a bit, I just don't feel up to my typical verbosity levels.

I see the source of the confusion now. You're being more specific than I was. When I wrote about HID lights producing UV and IR I mean light within that spectral range which are both clearly produced by HID lamps. I have no idea how much IR/UV is produced or blocked when you get on the far ends of those scales (far IR and EUV) but I did read this:

"Ordinary glass is partially transparent to UVA but is opaque to shorter wavelengths, whereas silica or quartz glass, depending on quality, can be transparent even to vacuum UV wavelengths. Ordinary window glass passes about 90% of the light above 350 nm, but blocks over 90% of the light below 300 nm."

Since we're not talking about ordinary window glass here I'm guessing HID lamps and better hood glass use the silica/quartz kind, and that should settle that.

The reason is that not all lights are the same. Fluorescents HAVE to be close because they lack penetration which might be fine over clones or seedlings but not as good for taller plants. Because fluoro has to be so close, it doesn't cover as much area either. LED is somewhere in the middle with better intensity/coverage than fluorescents but not as much as HID lighting.

My first grow was back in the 70's but I've never done side by sides with fluorescents and HID. Nor will I. I also won't do a side by side with incandescent bulbs even though I know you can grow cannabis with them if you have enough bulbs and deal with the heat.

I don't tell people what they can or can't grow with, you can use fluorescents if you want. I keep saying it; there's no one right way to grow but if you get...say...1g/w under the fluorescents (fluffier popcorn buds too) and you got .5g/w under the HID then you did something wrong under the HID because I know what they're capable of. Don't take it personally, it's not meant personally, I'm just trying to help people here.

I understand the dilemma (that goes back to the inverse law too) with beam angles, that's why CLW used 120 on the 5w diodes they run. If they ran 90, they'd have slightly better intensity but they'd lose coverage. The obvious thing I would try is 90 degree lenses on 10w diodes and just add more of them in a larger fixture to take care of the coverage. As far as I'm concerned, the myth (sales propaganda) that smaller LED lights can grow as much cannabis as larger HID lights has been busted by journal after journal. Even my local hydro stores say that with 5w diodes a 400w (actual draw) LED is about the same (yield wise) as a 400w HID. The idea that you can outgrow a 1000w hid with 20-70% less power is just not backed up by anything I've seen so far. That's why us older growers switched from fluoro to HID in the first place.

Even though I know that HID is a superior light to LED (and both better than fluoros for flowering cannabis), I still volunteer my time here in an LED forum helping people get the most they can with what they have.


Hope that helps...

SisterMaryElephant wrote:I'll skip around a bit, I just don't feel up to my typical verbosity levels.

I see the source of the confusion now. You're being more specific than I was. When I wrote about HID lights producing UV and IR I mean light within that spectral range which are both clearly produced by HID lamps. I have no idea how much IR/UV is produced or blocked when you get on the far ends of those scales (far IR and EUV) but I did read this:

"Ordinary glass is partially transparent to UVA but is opaque to shorter wavelengths, whereas silica or quartz glass, depending on quality, can be transparent even to vacuum UV wavelengths. Ordinary window glass passes about 90% of the light above 350 nm, but blocks over 90% of the light below 300 nm."

Since we're not talking about ordinary window glass here I'm guessing HID lamps and better hood glass use the silica/quartz kind, and that should settle that.

Erm sorry to inform you but you are mistaken, there are specific reasons as to why they are not designed to emit UV please read the excerpt below

"Most HID lamps produce significant UV radiation, and require UV-blocking filters to prevent UV-induced degradation of lamp fixture components and fading of dyed items illuminated by the lamp. Exposure to HID lamps operating with faulty or absent UV-blocking filters causes injury to humans and animals, such as sunburn and arc eye. Many HID lamps are designed so as to quickly extinguish if their outer UV-shielding glass envelope is broken."

The arc tube itsef is made of aluminum oxide ceramic which is resistant to the corrosive effects of alkalis like sodium. this by itself will block the transmission of infrared from what I remember the actual glass tubes are made from borosilicate and indium this also blocks infrared transmission so unless they have changed the construction my comments stiill stand, i.e they produce UV and IR but none (to a negligible amount) is transmitted to the plants hence (a big reason why the tubes will get hot) its not really a factor that needs to be considered when comparing grow lights as none are really emitters of noteworthy (if any) amounts of IR which was actually my original comment

SisterMaryElephant wrote:The reason is that not all lights are the same. Fluorescents HAVE to be close because they lack penetration which might be fine over clones or seedlings but not as good for taller plants. Because fluoro has to be so close, it doesn't cover as much area either. LED is somewhere in the middle with better intensity/coverage than fluorescents but not as much as HID lighting.

My first grow was back in the 70's but I've never done side by sides with fluorescents and HID. Nor will I. I also won't do a side by side with incandescent bulbs even though I know you can grow cannabis with them if you have enough bulbs and deal with the heat.

I don't tell people what they can or can't grow with, you can use fluorescents if you want. I keep saying it; there's no one right way to grow but if you get...say...1g/w under the fluorescents (fluffier popcorn buds too) and you got .5g/w under the HID then you did something wrong under the HID because I know what they're capable of. Don't take it personally, it's not meant personally, I'm just trying to help people here.

What do you mean not all lights are the same??? You do realise that they all emit exactly the same type of light right??? The only difference is the way go about it.
Most people hang fluorescents to far away treating them like they are a HID that is the problem I see time and time again, as to coverage you can get a larger "evenly distributed footprint" with fluorescents 8 x 4 ft tubes can be spread evenly over a meter square for an equal distribution of light over the area, a HID cannot do that so that is double the advantage to fluorescents, I can only surmise that actually it was you that had taken the wrong approach with regards to how you set your lights up, it's not a dig it's merely an observation As to figures it was all dependent on strain, but with the better ones I could get around 0.9g/w with HID and around 2g/w with fluoro, so the figures were none to shabby

SisterMaryElephant wrote: I understand the dilemma (that goes back to the inverse law too) with beam angles, that's why CLW used 120 on the 5w diodes they run. If they ran 90, they'd have slightly better intensity but they'd lose coverage. The obvious thing I would try is 90 degree lenses on 10w diodes and just add more of them in a larger fixture to take care of the coverage. As far as I'm concerned, the myth (sales propaganda) that smaller LED lights can grow as much cannabis as larger HID lights has been busted by journal after journal. Even my local hydro stores say that with 5w diodes a 400w (actual draw) LED is about the same (yield wise) as a 400w HID. The idea that you can outgrow a 1000w hid with 20-70% less power is just not backed up by anything I've seen so far. That's why us older growers switched from fluoro to HID in the first place.

Even though I know that HID is a superior light to LED (and both better than fluoros for flowering cannabis), I still volunteer my time here in an LED forum helping people get the most they can with what they have.

Hope that helps...

This comment here I could really go into but it will take to long and as time is a bit of a premium for me atm I will only lightly touch upon the subject. As to diodes size not sure what the current state of play is but 1w diodes were the most efficient, is having deeper penetrating diodes really a solid approach well I would question it on the basis show me a leaf that allows light to pass, plus now I have to hang the fixture at a greater height which means I have just lost the initial advantage/efficiency by the square for every foot away I have to keep the fixture, this now means the light becomes less intense over the distance so what have you really gained by the bigger diodes, maybe you have gained a little somewhere but you have lost elsewhere, there are many trade off's with LEDs which I do not think the bulk of the manufacturers have thought about, maybe partly due to limited backgrounds in engineering.

As to Fluoro vs HID all I can say is I have had my successes (Flouro's have a fuller spectral emission than HIDs for the record) and I know there are others I have met in forums who have had similar results so it's not some kind of fluke, it can be explained mathematically to an extent and that's good enough for me, I am sharing my knowledge and I guess it's up to the reader whether they take it or leave it.