Lol yeah pretty soon our single posts will be 1 page long each

That is where you are mixing two seperate issues into 1 box that is not the case. Your talking about light intensity and then coverage, although they are related to each other and both have an effect on your harvest, they are in fact two seperate issues. When the testing of micromoles was done it was never stated that the light intensity is 2000+ micromoles 12" away from the light source only for a specific area. That is just the light intensity at that distance, what you want to put in the area under it and how many you can fit is upto you. It doesn't change that at 12" that is the intensity (power) of the lights.

Coverage and penitration are two things that will be effected by your style of grow and the number of plants in your area (IE: you have 4 plants, I have 15-16), however this things/factors do not and will not change the fact that at 12" away the LED is over 2000 micromoles which is slightly higher reading then a 1000W HPS (HID). I don't know what you been smoking or where you recieved your information but, the distance is the exact same 12" away from the light source, and it was a 100% equal test. 1000W HPS puts out the higher micromole levels of HID, so that is why test was between a gs600 and a 1000W HPS. What I was not able to find out was the make and quality of the 1000W HPS blub, as we all know with anything there is great quality and lesser quality out there. If they were in fact basing the science off of what you were saying (smaller LED in smaller coverage area vrs a larger HID covering a larger area) then I would agree that would not be an equal test. However you me and LED companies have not been the ones to make those decisions of how they rate things and on what factors they compare, science does.

LED is very complex and there are many issues and factors to consider, that is why I have taken exception to you cross mixing seperate factors.

Will LED not cover the same area as 1000W HID? Well yes and no. That all depends on the angle of the lens, if a company is using 120 degree lens then they can have just as much coverage as HID. There is a difference between effective coverage and coverage though. Just because a LED light system can cover the same area (4 X 4 or 4 X 5) does not mean that it will do it just as well or better then a HID light or even a different LED light.

I didn't say that coverage is just a small part of the debate, I said it is not the single and only deciding factor. There are many issues that are all interconnected that each have to be taken into account for. At least with LED there is. HID you just put up a light and pump out massive amounts of wasted energy, you don't know or fully understand why you have to pump out those massive levels of wasted energy, but decades of playing around with HID lighting has shown that is how you get better yield results.

The only hype is been the outright lie by HID companies for decades with regards to Lumens. Lumens have zero, nada, nothing to do with how lighting effects or is absorbed by plants. Yet that is how they been rating their lighting systems for decades.

Put it this way, you take a flashlight (10,000 candle whatever+ light) and shine me in the face, I take a little LED laser pointer and shine you in the eyeball. Sure you just blasted me in the face with a spotlight and blinded me, but my LED pointer could have given you retnia damage for life. So which one is more effective? That is exactly what your doing to your plants.

You keep saying lets compare apples to apples, then you go and compare apples to pineapples.

Yes I agree that 5W diodes can make a difference, I just said I don't personally feel that at this time they justify the additonal cost (yet). First I have to see the results from my 3W single chip system. That is another seperate factor, 1W 3W 5W 20W, some LED companies use this rating as a way to mislead customers out there. What I mean by this is that a 3W single chip LED isn't actually using 3W of power, LED's actually use lesser amounts of power then they can, more so that it is the max wattage those chips are able to handle. If you put 3 1W LED's on a 3W chip, does that equal the same as a 3W single chip? Does that make that a 3W-3chip as powerful as a 3W single chip?

Lmao yes I too have personally experienced this, as for "Kush" I find thatfunny as well since the term Kush used to stand for the region of indica strain where it was grown. Now a days everyone says Kush for everything and anything. I hear Kush and my brain just shuts off now.

I once again agree 100% that many LED companies overstate their coverage, which is why it is important to first compare LED to LED before you try and compare LED to HID. There are many growers out there using LED lights from all types of companies, some have gotten good results and some not so much. This helps to give an understanding of what you can achieve and accomplish with LED lights however once again there are a ton of other factors that need to be included in that assessment. Things like conditions, spacing, nuets, proper care, lighting rotation (meaning turning your plants and changing their position in the grid, if your able to), just to name a few.

Part of the high cost of LED lighting is due to the actual makers of the LED's, like cree, bridgelux, ect. Some of those makers make great blue lights or red lights, but it is really hard to find one maker who makes great any color lights. So you have to mix and match brands to get the better results. That will eventually come down in price and cause cheeper prices for customers. Thanks to people like myself who have already spent higher costs now for LED's compared to future costs in the future, there are enough of us supporting the industry to make companies be able to afford those future savings.

Maybe in 10 years we will look back at this and laugh that we were debating over 1W and 3W LEDs when the standard is now 15W or 25W ect. Problem is that currently there are not enough LED makers to supply quality 5W LED's that would be good enough quality for growing. Yet another reason why I am and was not excited about that solarstorm, who knows maybe they have a source on the only good manufactures of 5W LED growing lights?

Some LED companies have said that LED's are 80% more efficient then HID, but I agree with you that it is too hard to say exactly what number is the safe one of right one. Bottomline is that LED have the edge in this part of the issue. Suprised you didn't say this is just hype too

I am glad that you finally admitted that LED's in some situations can be effective as HID lighting.

Got to run out for now but hope your feeling better and look for your reply later.

Jesus I hate when forums eat a long reply...

That's where YOU fall for the hype, micromoles at 12" is just a measurement, put on paper, used for marketing claims and it isn't the only thing that determines if a smaller LED can "REPLACE" a 1000w HID. It doesn't matter if an LED has 2k micromoles at 12 inches if the smaller LED can't cover the same area. It doesn't matter if the LED has 2k micromoles at 12" if the suggested height is 18-24 inches. It doesn't matter if the LED has 2k micromoles at 12" if the light can't penetrate as deep as the light it claims it can replace.

What REALLY matters is real world growing and that is not as "complex" as you imagine. I've laid out the challenge and if ANYBODY thinks their smaller (300-700w) LED can "replace" a 1000w HID then it should be easy to prove me wrong. A SOG grow, flowered at 10-12 inches, spaced 1 foot apart. That's 20 plants for the 1000w and, using your GS-600, that'd be 14 plants based on the suggested coverage for that LED light. I don't care which LED you pick and it doesn't matter what lens angle they have, the 1000w HPS will beat any LED light that is 30-70% smaller, even if they claim it will replace the 1000w HID and no matter what the micromoles are at 12 inches. That's my story and I'm sticking to it.

Wrong, coverage and penetration are NOT effected by grow style. The 1000w HID will cover up to 20 sqf no matter if you grow trees or SOG. The 1000w HID will penetrate just as deep no matter whether you grow tress or SOG, even if the SOG plants never get tall enough to exceed penetration. Same with LED. The number of plants that you can fit in a specific area is determined by grow style. If your area is the limitation you plan a light for the area. If one light won't cover enough area you either get a bigger light or add more lights. As I've said, you plan the area based on the light you have/want or you plan the light based on the area you have/want.

Saying that a 300w - 700w light can replace a 1000w HID based on micromoles alone is like saying that Toyota Hybrid can replace a Hummer because they both have 4 wheels. Sure, the Toyota does use less gas but it wont do the same things that the 4x4 Hummer can.

Yep, "Kush" is the new "Chronic."

Of course LED will get better and cheaper as more and more people start using them and I don't just mean growers. HID was very expensive until it matured and became widely adopted.

Finally admitted? When have *I* ever said differently? What I've said, repeatedly, is that many LED companies overstate their coverages and that the claim that much smaller LED lights will replace a 1000w HID are nonsense. I've also stated the FACT that more w/sqf is better than less w/sqf.

Lol I know everytime I start a reply I always do it with the mindset that it will be shorter then previous posts, yet it always ends up being the same or longer

Let's start off where I disagree with your views. First off you wouldn't compare a Toyota Hybrid to a Hummer (LED to HID is not Hybrid to Hummer, not even a SUV), it would be more like hybrid to another similar car such as a ford focus, you would compare them based as they both are the equivilant of a 4 cylinder, not because they both have 4 tires. I mean a gocart has 4 tires does that make it a car? A bike only has two tires, but can still out perform a car with 4 tires.

Just the same as LED to HID, You wouldn't compare a gs300 to a 1000W HID (MH or HPS) light, because it can't on any level. However you could compare it to a 600W or lowers HID light and depending on the degree of difference, IE: gs300 vrs 600W MH or HPS, gs300 vrs a 400W MH or HPS, gs300 vrs a 250W MH or HPS, it can in fact compare to those lights in many aspects. Will it do as good of a job in all situations as a MH or HPS? No, any LED company that claims that it will is just lying. However, depending on your situation, your method/style, space, experience, it can in some cases be just as good or better.

Of course coverage and penetration are effected by grow style. I should have been abit more clear with my wording on what I ment by that statement. What I mean is that the degree of how important those issues are important to you as a grower changes based off your own personal needs and expectations. I am not saying that they are not important, rather that the level of important can change with your method.

I think we can both agree that there are a number of key issues that are important to consider and will effect your grow. Space ( total area to grow in), Lighting (method of lighting, HID, LED, CFL, T5, candle light ), Coverage, Height of plants (penetration issues), plant spacing (distance between plants and the size of space you give them to grow). These are just a few off the top of my head, I am sure there is more we could think of and agree upon.

Now when your deciding your grow based on all your requirements and limitations, how do you personally rate which is the most important issue compared to the rest? It changes with each individual grower because they all have very different issues that they are dealing with. Could be money, space, or whatever. That is my point. A grower who is looking to bloom huge 6 foot + tall trees will have a greater level of concern then a grower who is doing a SOG or a SCROG, just like a grower who is doing DWC has different needs then a soil grower.

Obviously in a perfect world I would want to have the best conditions or supplies for all those factors, but if for some reason due to my limits I am unable to do so, it is smart to consider the "pecking order" of importance of factors I am willing to let slide down the list and to what level I am willing to allow them to decline in importance.

How the micromoles issue comes into play, it is more like comparing two cars traveling a set distance. Both a gs600 and a 1000W HPS have an output of roughly 2000 Micromoles at 12" away from the light source, that is just a FACT plain and simple. If your Hummer and my hybrid (as you say) both ran a time on a speed track of 0-60 MPH in 5.2 seconds that they would be comparable at that distance. Just because a hummer would blow away the hybrid after the inital quarter mile does not change the fact that at that distance they do compare.

As for a real world challange I am already doing it and I have a way to judge my final results that is extreemly fair to both LED and HID. Personally for me it would not be worthwhile to change my method from it's current state for many reasons, 1. doing a SOG would not increase the amount of harvests I can do in a year. 2. the amount of work and effort I would have to put into changing my current system would be greatly increased compared to my current method. 3. I would have lighting that I currently have that would not be useful anymore. 4. I would have to spend additional money to run this new setup. I feel that spending close to $9,000.00 as I have just done is more then enough money out of pocket. 5. I would not have any real world growing experience and results to compare it too, so I would not be able to judge with as much data and experience as I currently able to do now.

For the record the suggested height is 12-18" for blooming plants, 18-24" in veg and 24-36" for seedlings and clones. The distance you have your lights changes as your plants grow and enter different cycles, that is for any lighting source unless your growing outside with the sun.

If I made that change to my entire set up I would not be able to recieve the required amount of yield that I am expecting to gain with my current set up. With my space and lighting conditions I would only be expecting to recieve roughly 54 Oz going to the high end yield based off that questional report of 3/4 LB off a 4 X 4 area. With my current method I am expecting to recieve anywhere from 30-85 Oz on the high end. If I do end up getting in the lower range yield (30ish or less) then it would be worthwhile for me to consider switching up my method. I am hopeful that it will be closer to the 60 Oz mark, however as long as the quality of the bud and the taste and texture is still there then the real comparable mark for me personally is around the 40-45 Oz range. If I am able to achieve those same results then I will know for certain that I was able to replace my HID lights with LED.

I haven't been on GS's website in abit but I am pretty sure they used the phrase rival rather then replace when talking about subbing LED for HID. However I do know that the majority of LED companies out there use that term "Replace".

Werll based on your view points and comments I personally get the impression that you don't feel that LED can do a comparable job and or replace a HID lighting system. I do not know if I would agree that LED companies are overstating their coverage areas, I mean if a light can cover a larger area due to it having 120 degree lens instead of 90, then it can in fact cover a larger area. Will it do as good of a job as a HID? I doubt it will, but then again I doubt it would do as good as a job compared to a similar LED light with 90 degree lens. That is why I have said many times that you need to compare LED to LED first before you compare LED to HID, simply due to the fact that not all LED lighting is created equal.

Nobody is saying that more w/sqf is not better then less, I don't really see how that is an issue with the topic at hand? What I did point out and question is that how you base those w/sqf and how they are actually used in terms of effeciency for the plants is something to consider. Like I said before, If I am using 1000W HPS light and getting 40w/sqf compared to gs600's in the same area and getting 33w/sqf, yet I am able to use that light more effectively which is really the higher amount?

The way I will be able to tell in a matter of this current cycle upon it's completion, is to compare the quality of the end result vrs previous 3 years of history, and the average yield off the same comparable number of plants during the same period of time. If my theory is correct, as so far it has shown to be (in way early stages of completed cycle), and my yield and quality is still comparable to previous results, then I would have in fact been getting a better efficiency from the lower number of wattage of LED making it in fact comparable to HID (MH and HPS) and possible to replace HID with LED.

Only time will tell for sure, but atleast my test will remove doubts about this issue.

I'm trying to condense now too...

I disagree. What we're talking about is the claim that a smaller LED can "REPLACE" a 1000w HID and the only thing that the LED companies can come up with to TRY to show that they're equal is micromoles at 12 inches. Therefore, to me, comparing a Hybrid (smaller and that uses less fuel) to a Hummer (more powerful and versatile) based on the fact that they have 4 wheels (micromoles alone) seems pretty accurate.

Right and the GS company doesn't claim it's 300w light (at 240w draw) can replace a 1000w HID but it does say "It delivers more light intensity per square inch than a 600W HPS" that's more than twice as powerful. So it implies that it can "replace the larger HID but it doesn't actually say that verbatium. The GS-600 makes similar claims regarding 600w (550 draw) versus the 1000w HID. Similarly, prosource makes similar claims with their 180w and 350w UFO lights, they say "output" and "absorbable" light. However, the 357 magnum light company claims, outright, that it's 180w light can replace a 600w HID and the 357w light can replace a 1000w HID and I don't buy those claims either. Virtually all LED companies make similar claims.

I said that I'd post if I found the "no heat" claim again and from the 357mag site: "•Virtually Zero Heat By Product" I know "virtually" is a disclaimer but that's still the marketing (hype) implication. If I run across another, without the disclaimer, I'll let you know.

Of course there are many factors in a grow, that's like saying air is important. Of course priorities vary and that's why LED MIGHT be better for some people. If the main concern is to use the newest lighting technology and startup cost is less of a concern, then LED would be logical. If the main concern is the ability to flower trees, then LED would not be a logical choice. There is a whole world in between though and now I'm repeating what I've said many times. You either plan your light on your area or you plan your area on your light. If space is your main concern then you plan a light that will work in your area and then you add your plants depending on your grow style.

You are doing similar grows but not equal, side by side, grows. It will probably help differentiate but they're not equal comparisons. If I were doing a comparison I'd do it side by side with the only differences being the light and the area covered by the light which limits plant numbers. You're already talking about doubling the nutrients this grow. I'm still curious about how the final result will compare but this grow is not "equal" to your previous HID grows. I said it before, I think you'll end up with more internodal stretch and lighter/fluffy "popcorn" buds, especially lower on the plant but we'll see what you think of the results when you have them.

Doing the math, you have 3 x 550w worth of flowering light divided by 29 grams per ounce (rounded up) = about 57 ounces at 1 gram per watt. 28 ounces at .5 gram/w and 48 ounces at .85 grams/w. I know g/w doesn't take into account veg wattages and veg time but you can take the total dry harvest and figure out what your yearly total would be and then you would be able to compare that to other grow styles, like SOG, if you try that in the future. If it takes you 4 months to clone/veg/flower then you get 3 harvests per year, with a 3 month cycle you get 4 per year. With SOG you might get 5 or 6 smaller harvests per year but you get the point. I think yearly averages are better comparisons for total yield. I guess, then, you'd need to divide the total cost of production (water, nutrients, power, media etc) by grams to get a cost per gram to grow. The cost of durable equipment (like lights, fans, tents, etc) would have to be divided by 10-15 years and added to the yearly cost. I think then we'd have a better estimation of how much different methodologies truly cost. Even then, results would vary year to year and even grow to grow. Disasters happen...

I don't think a much smaller light can replace a larger HID, no, but surely some size LED could replace some HID. My estimation, using the GS LED products, is that you'd need a 1200w LED to compete with the 1000w HID and even then, trees would be out of the question. It doesn't matter how wide the lens is if there's not enough power too. For example, the 357 mag plus says it will replace a 1000w light and even if it had a wider angle lens, so that it would cover 20 sqf, it's still only 357w and that's 18w/sqf. There is NO way that 18w/sqf LED will compete with 50w/sqf HID. I just cannot believe that it's possible. Doing the same math with the GS-600 = 27.5w/sqf, even if it had wider angle lenses and we didn't grow trees, I don't believe that 27.5w LED will compete with 50w HID either. Using the GS-1200 (coming soon) it will cover the same area but since it has to be so powerful to cover that area it uses 55w/sqf, so, as long as we weren't growing trees, *that* LED might actually replace a 1000w light but it will cost about $2,500.00 each (guessing) too.

I bought up the more is better (conditionally) because a number of people do skimp on lighting, using less than suggested levels. You admitted doing that yourself both with HID and LED. I use 50w/sqf for HID because that's sort of an industry standard, it's been proven in the real world. With LED it becomes a little more murky due to lens angles (your favorite) and other variables from manufacturer to manufacturer. However, I've seen several experienced LED growers suggest that the "magic" number for LED is around 40w/sqf and the prosource commercial grow video uses 45w/sqf LED. So, for example, if a LED light *could* cover 20 sqf at 40+w/sqf it might be comparable (aside from penetration) to a 1000w HID.

I thought we agreed that it's difficult to put an actual number on what percentage of HID/LED light is usable? That's why I don't care about micromoles nor lumens, I KNOW that if I put 50w/sqf HID that I'll have enough light for quality results. I might go higher but never lower. If that magic number for LED is 40w/sqf, that's what I would use if I ever grew with LED. I'm not saying that 40w LED is the right number (40-45 maybe?) but that's what some people are suggesting. 40 compared to 50 is a 20% difference and that might be right but we still don't know, for sure, because we're still learning what band/spectrum plants are really using...thanks, in part, to experimentation with LED. Few people thought that green light was useful but it turns out that it is. Perhaps "full spectrum" is more useful than we all thought? No doubt that HID loses a lot of energy as heat but maybe spectrum plays less of a role that we once believed. Either way LED is still too expensive compared to proven technology like HID, imo. Prices will drop and technology will improve, eventually, but the prince of lighting is not ready to take on the king.....yet.

AfganBerry wrote:I do not know if I would agree that LED companies are overstating their coverage areas, I mean if a light can cover a larger area due to it having 120 degree lens instead of 90, then it can in fact cover a larger area. Will it do as good of a job as a HID? I doubt it will, but then again I doubt it would do as good as a job compared to a similar LED light with 90 degree lens. That is why I have said many times that you need to compare LED to LED first before you compare LED to HID, simply due to the fact that not all LED lighting is created equal.

Let's break this down into smaller chunks and see where we can agree.

This post will only deal with whether or not some LED companies are overstating their coverage claims.

Personally, I think that I already proved that many do overstate so I'll go over it agian.

If we can agree that proper coverage is going to require at least 40w/sqf (LED) this should be easy so lets start there. The GS LED lights all average out to about 40w/sqf based on their stated flowering coverages and they're one of the few that I think are at least close. I'm not sure that 40 is exactly right but let's use that for now. Also, the prosource video that's been linked a few times on this site shows a commercial grower using ~400 180W UFO LED lights (one over each plant, spaced 2 feet apart) that averages 45w/sqf and they claim to get very good results at 45w/sqf. Additionally, nickgreen (one of the admins here) suggests 40+w/sqf for LED as well. So, do we agree that 40+w/sqf provides "proper" coverage regardless of the lens angles, number of diodes and watts per diode?

All you have to do to see that many do overstate is look at how many claim their various lights with various wattages can properly cover their suggested areas at 11-30w (not enough) and you'd have to admit that they're over stating. If you "need" 40+w/sqf LED to properly cover an area and the marketing info is claiming less w/sqf then either they're over stating their coverages or they're stating coverages for a crop that's different than ours. I also think it's safe to say that they all target cannabis growers, even if few of them say that for legal reasons. Tomatoes, roses and cucumbers, for example, are day-neutral plants, photoperiodismically speaking, and therefore are not affected by a short or long-day photoperiod. Instead they "flower/bloom/fruit" based on octogenetic aging or vernalization. Therefore most people that read the advertised coverages will assume that it's for cannabis and the various web sites surely don't say what crop those coverages are for if it's not cannabis.

Additionally, you posted the following, in this very thread:
"Over the last few months, it has become blatantly clear that the primary reason people are purchasing LED grow lights is NOT to grow tomatoes and herbs."

"While some grow light companies flat out overstate their recommended growing area simply to dazzle the visitor into purchasing, others have not-so-sinister reasons for their claims. The former is out to make a quick buck - customers be damned - and they end up shooting the industry in the foot by perpetuating negative reviews. This is especially true of low-wattage LED panels and spotlights (LED grow panel review). The latter is trying (sometimes to the detriment of its bottom line) to keep neutral by not catering to any particular customer niche, i.e. Cannabis Growers."

and

"Let me be blunt here - a 90W LED grow light CAN support a 4'x4' footprint but only during the vegetative growth of plants like lettuce, herbs, and some fruits and vegetables. If that is what you are wanting to grow then you will do just fine. For those of you growing cannabis, coverage expectations need to be put in check."

For our crop, a 180w LED light will not cover a 4x4 area at 11w/sqf no matter what lens angle they use. It might "illuminate" the area, given the right lens angle but not at a level (40+w/sqf) required for "proper" coverage. Agreed?


I think it's obvious that many, if not most, led companies overstate their coverages for numerous reasons. If we can all agree here we could move on to something more controversial. Feel free to suggest the next item for discussion if we agree here.

Lol we are not doing a good job of condencing

I was speaking about doubling the nutrients in my current grow in order to keep up with the amount of nutrients I was using under HID, however as of my last update, I noted that when I did the orgional feeding at 1/2 strength nuets I am now experiencing nuet burn on my plants. Not a major amount thankfully but enough of a concern to make my second feeding only water.

At this time of year the HID lighting would have been uncooled and roughly a temp difference of 10 degrees. I have already used less water and way less nuets under LED then compared to HID (uncooled). I don't even have a need to run my 6" fan to circulate the air and lower the humidity. While the fan was running before I put the plants in the tent it lowered my humidity to 50% or lower, so I turned it off and added a pail of water to help bring the humidity up to 60%ish. I have removed the pail and fan is still off. So I will see how the humidity level changes, that is something that I monitor daily.

To make sure there is enough air flow in my tent I open the flaps, have an osilating fan running 24/7 inside and can open the doorways if needed. The temp has always been between 78-80 degrees and hasn't changed.

I jumped the gun abit with considering "double nuets" because I doubt I will even get upto a full strength feeding during veg cycle. Tipically at this point in time of the veg phase there would have been 3 to 4 feedings under the HID. Normally would have been 1/2 strength, 2/3rds strength, full strength and then either 2/3rds or 1/2. I have only required 1 1/2 strength feeding and 1 water only feeding under LED. Currently I am running at least 1/3 of the amount of nuets under LED as compared to HID.

I am doing a comparable grow, it isn't side by side, but due to the amount of space I have available and the start up cost I could not afford to waste the extra money on HID lighting. The previous grows I did not have 100% control of the space, which I now do. Those lights are not available for me to do testing with.

I am running a setup where I will be blooming out every 8 weeks, so 6 cycles a year. While the 8 weeks of bloom are happening there is 3 weeks of cloning and 5 weeks of veg happening at the same time. The reason why I personally am not considered with grams per watt is that during the past 3+ years we have only been keeping track of the number of Oz we have been getting off the number of plants that were grown during that cycle. There would be too much room for error if I started tracking this current grow off of that kind of numbers and hot having accurate data to compare it to.

If I know that based off an average of 15 plants over the past 3 years that we were getting roughly 1.76 Oz per plant and with the change to LED I am able to get 1.5 Oz per plant then to me it is worthwhile to have made the change to LED. If it is way lower then not so much, this is all just guess work atm so I will have to wait and see the results before I make my decision.

That pretty much is the whole story there in a nutshell. Will have to wait and see what type of results I get, the yield, total nuets used, water, and energy costs. As time goes on we will all know more.

Any information about my grow (current or past) that you are interested in or something in the pic's that you have questions about?

I agree that LED is a lot of test work as I am currently experiencing that as we speak.

No I don't agree that 40w/sqf is the magic LED number regardless of lens angle, number of diodes, and watts per diode, at least not at this time. That might change depending on the results I see after my first full harvest under LED.

I doubt that I would even agree on that once I have a full harvest under my belt under LED lighting, as not all LED lighting is created equal. I mean if I had a gs600 (550 actual watts) with 90 degree lens (which they are infact) and I had a gs600 with 120 degree lens that would make a huge impact on the results of my grow when you compare the two. Because the 120 degree lens is spreading out over a much larger area the light intensity will be drastically reduced as you increase the distance away from the plants. Even though they are the same amount of watts they will not be equal.

This is where I think that you are over simplifing a very complex issue in order to compare LED to HID. Is 50W/Sqf good for optimal results under HID? Yes 50W and above. Why? Nobody fully knows or understands why. How much of the actual light output under HID is used or absorbed by the plants? Nobody knows fully. How much of the reflected light (of the 360 degrees that the bulb is actually putting out) is actually able to be used by the plants and what amount of that reflected light has a reduced light intensity? Nobody fully knows.

When it comes to LED you can't base logic that works for HID and transplant it to LED.

Those quotes that I posted was a quote from another source. When they were speaking of low wattage LED pannels, they were refering to the very first LED grow pannels (IE: 10W-50W) that were a complete joke and really hurt the industry. In my local grow shop there is a 14W LED Grow pannel that you can buy for like $120.00. Good luck trying to grow a blade of grass with that.

I have said time and time again you need to compare LED to LED before LED to HID.

Best thing is to wait and see what kind of results I get and we both will have alot more information at that point in time. Then I will be in a better position to decide what amount of LED lighting is proper for a 4 X 4 area.

As for Nickgreen I have never spoken with them and do not have any idea of what their experience is growing with LED and for what purpose or style of growing.

I noticed that too, I need to try harder.

As I mentioned the amount of nutrients used at such an early stage could vary from grow to grow, you mentioned in your journal that the roots needed more development. I think that'll stabilize as the plants mature.

Here, I can vent my hood exhaust into my living area to reduce heating costs in winter and run it outside when uneeded. Clearly, geography has an impact too.

That's still an example of running unequal (yet similar) grows instead of side by side grows. If I were going to to a comparison grow, I'd be using the same clones, using the same nutes, with the only differences being the lighting, square footage (if different wattage lights used) and whatever additional environmental adjustment required to keep temps, humidity, etc the same in each room. I think hydroponics would be better suited for such a comparison since that would keep things more equal too but that's a personal choice.

I don't think there is a perfect way to track/compare results. Yearly yield divided by total cost averaged over 10-15 years might be close but even that has external factors. Over 10-15 years any grower should get better so even the same grower won't have equal grows year to year. My yield this year has already been affected by my back injury too. I wish there were a database were people could plug in a bunch of variables and compare their results to similar grows but there isn't. I guess it's the science + art deal again...

Are you basing your "worthwhile" assumption on weight alone or also on other factors?

I think you're right, what we'll need to do is wait for results and see how you think they compare and then evaluate if the added costs of setup is worth the energy savings and results. Everyone and every grow is different. One of the SolarStorm reviewers is going from fluorescent to LED and I'm sure his results will be better but I'm not sure how LED will compare to an experienced HID grow. Now that things are picking up in the forums, perhaps more people will be able to add to the debate.

I'm not saying 40w is exactly the right number either, it's possibly more. I ran into another LED review website, today, that suggests 200w for 4 sqf which is equal to HID's 50+w/sqf general rule for high quality. Whether it's 40 or 50 though, surely you're not suggesting that 11, 20, 30-ish watts is enough for the high end results?

I assure you that changing the lens angle on the same wattage light isn't going to cover more area in a proper manor. It'll "illuminate" more area but, as you mention, there will be less w/sqf and intensity will suffer. If a 550w LED with 90degree lenses only covers 3.5x4 @40w/sqf, changing the lens angle, to 120 degrees, to make it illuminate 5x5 (totally made up) would still reduce the consumption to 22w/sqf and I submit that it's just not enough for a proper grow no matter what the angle. The only way to properly cover more area, imo, is to add more watts, not change lens angles, assuming that you're sticking to the 40+w/sqf recommendation.

You're right, we just don't know, numerically, what is used and what is wasted but we DO know that, with HID, 50+w/sqf is what is recommended to get high quality results. I've heard 40-50w/sqf for LED, depending on the sources. The only places that I'm seeing less being suggested as optimal, is LED sites that, I believe, are overstating their coverages for reasons that can only be imagined.

Again, I'm not suggesting that 30-39w/sqf won't grow flowers that are "potent" but the less light used, the less dense the flowers are and more internodal stretch you'll see. Will 39w vs 40w be noticeable? Probably not but 11w vs 40w certainly would be noticeable, 30w vs 40w probably would be and 35w vs 40w might be. I'm sure you'd see a difference between 40w and 50w too.

The *same post* that I quoted above, regarding overstated coverages, also says:
"90 Watt 4' by 4' 2' by 2' (veg - flower)
180W 5' by 5' 3' by 3'
350W 6' by 6' 4' by 4'"
That suggests that 20-22w/sqf in flower is acceptable but I seriously doubt that too and lens angle won't change the number of w/sqf. Your 550w GS-600 light won't even properly cover 4x4 for flowering according to their own website, how can 350w cover more? Lens angles won't do that so either they're overstating (in regards to our crop), or GS is understating and I don't think GS is understating proper coverages. They're clearly not talking about 14 watt panels, they're talking about 90-350w LED lights. I saw a post, elsewhere, where a guy wanted to know if he could flower with 8w LED. 14w is almost double the yield!

I agree that results are what matters, in the end, but we can still debate or it's going to be pretty boring around here until people start harvesting.

I've only read nickgreen's posts too but he clearly has more LED experience than I do and his claim of 40+w/sqf happens to be what GS suggests is proper coverages for their lights.
Here's what he said on page #1 of the "Suggestions for a LED setup" thread:

nickgreen wrote:The 90W Illuminators are good lights and their coverage areas are accurate . . . let me explain.

If you look on the page:
http://www.prosourceworldwide.com/Illuminator-90W-UFO-LED-Grow-Lights-p/illuminator%20ufo%2090w.htm

You will see that the coverage area of 4x4 is for vegetative growth while the max coverage area for flower is 2x2 . . . so when it comes to outfitting your space, just focus on the flowering coverage and go from there. Each 2x2 area needs at least a 90W and can take up to the 180W for a 2x2 - it just depends on the type of results you are looking for.

With LED, I like at least 40W per square foot for commercial grade results.

As I replied to him: 90w in 2x2 is only 22.5w/sqf so that is an overstatement of coverage if 40w/sqf is what's needed for high end results. I don't know anyone that pays the high cost of LED lights hoping for low/mid grade results. Everyone wants high end results, they just want to get them as cheap as possible which is why we're having the LED vs HID debate too.

Also the prosource LED commercial grow video (on youtube) is using 45w/sqf and they claim high end results, although I saw problems with that claim in the video too so maybe 45 isn't enough either. That's another debate. YMMV...