Which kind of lighting unit do I choose?

[GSZZ]

We are spoiled rotten at the moment with all manner of different lighting sources from the old CFL, T5, MH, HPS to the newer 400v HPS, DE HPS, CMH, and LEDs. With extravagant marketing claims and an ever advancing science It can get confusing pretty quickly trying to understand and work out which is going to work out best for you and your applications, I've typed this up one way or another a few times in different threads but I am feeling inspired today(maybe it's the premier sweet ) and we get threads asking which lamp is better etc (secret: none of them are better than the other!) a lot of the time.

So go ahead and bang the kettle on and get rolling a joint, and we'll go through what considerations we need to make an informed decision on grow room lighting, regardless of the type of unit, and without letting sales and marketing hype lead to an expensive mistake.

Photon Particle Flux (PPF) and Photosynthetically Active Radiation (PAR)

First up - What is PAR? Google says:

Photosynthetically Active Radiation (PAR) is the amount of light available for photosynthesis, which is light in the 400 to 700 nanometer wavelength range.

In times past growers have used lumens as a way to determine how good a lamp is, but as the science has evolved we've learned that lumens is more or less irrelevant when it comes to growing plants as lumens is the measurement of how bright something is to the human eye, and we can only really see 500 - 600 nm with any real accuracy. We know now that plants use 400 - 700 nm, so we can see high lumen lamps don't necessarily make the best grow lamps.

PAR vs Lumens

Some parts of the PAR spectrum perform better than other parts of the PAR spectrum at different tasks, for example red photons don't require as much power to make them and only perform the task of photosynthesis. Where as Blue light requires more power, but also contributes to other none photosynthetic but potentially yield enhancing benefits like greater water retention and management and bigger root systems, where as other colours may be incredibly poor at photosynthesis but have quality increasing benefits.

But the main purpose of light as we know is photosynthesis, and we all should know how photosynthesis works by now. So with that in mind, your plant can only perform the action of photosynthesis so many times before it's had enough - if any of you have ever had plants on a 24/0 light cycle will know there is some mid-light cycle depression where the plants generally droop and look a bit sad, this is because they've reached saturation point and generally want to sleep.

This is where PPF comes into things, what is PPF? PPF is the total amount of PAR photons emitted from a lighting source. Because the amount of photons that are emitted from a lamp are in the billions of billions, we use umols to make it a more manageable number to work with. A few typical HID examples (lamp brands may differ):

600w 240v: 1100 umols

600w 400v: 1175 umols

1000w DE: 2100 umols

315w CMH Agro: 601 umols

PPFD stands for Photosynthetic particle photon flux density, this is how many photons from your lamp/s hit 1 square meter a second. The upper limit for cannabis is around 1200 - 1500 umols per m2 before we start having to knock time off of our day light hours to compensate. So to keep things simple and without going into Day Light Integral, we want to keep the usual 12/12 for flower so stick with a saturation point of 1200 - 1500 umols per m2 . If we stick to that number we know it's possible to do 1 GPW or more from our lamps pretty consistently using the lighting hours we all know and love.

As a rough guide, I implore you to do your own research, we want to be looking at lighting levels as follows:

prop - 100 - 200 umols per m2

Vegging 300 - 500 umols per m2

Flowering: 600 - 1200 umols per m2

To give yourselves a rough idea of what PPFD you're working with or want to work with, simply add the PPF of all the lamps together and divide that by your total space in square meters. Without taking things like reflector losses, wall losses and other variables into consideration, this gives us a good base to work from.

So now we have an idea of what PAR, PPF, and PPFD is, it's worth noting that it doesn't matter what kind of tech we use if we supply the same PPFD we can expect the same sorts of yields. This is where it all makes sense - for example we all know that 1 GPW from a 600w is 21 ounces (and a bit), and from the above we know a 600w lamp outputs 1100 umols, and will output that in 1 m2 space total. So if you can supply 1100 umols in the same space as the 600, but for less wattage, we can still expect the same sort of yields.

Spectrum

So we've seen from above that plants use the entire PAR range, and we also now know that if we supply the same PPFD regardless of spectral output we can achieve the same sort of yields. But that's not really taking spectrum into consideration and what it can do for us as growers.

A phillips son-t 600w HPS spectral output

Unfortunately because the crop we grow is illegal, there isn't much research I've been able to find in the way of how different wavebands of light effect cannabis growth - apart from what we've collectively shared and learned over the years online - but there is plenty of info out there on a wide variety of other plants on the effects of different wavebands of lights. It would be foolish to suggest that cannabis doesn't benefit from these different wavebands of light, and we know from users own experiences that adding full spectrum to sodium lights, or growing entirely under full spectrum, can facilitate things such as:

Bigger yields, better root growth, better genetic expression, improved flavours, increased psychoactivity, more colour pigments, quicker flowering times and a whole host of other benefits. Plants naturally evolved and grew under the sun for millions and millions of years, it is sensible to suggest that a plant will perform the best it can under a full spectrum.

Phillips 942 and 930 agro 315w CMH spectal output

So with that in mind, for home hobby/medi growers it is IMO advisable to grow the best you can either for recreation or medicine is to grow it under full spectrum. Whether supplementing HPS set ups or entirely full spectrum.

Cost

Cost is pretty simple and it all boils down to one thing: Efficiency! How how umols do we get per watt? From this we can work out how many units we're going to need to reach our target PPFD, how much they're going to cost and how much its going to cost to run them. From there we can make as informed as choice as we can on lighting based on our applications, as we can work out how to deliver the best spectrum and PPFD within our budgets.

Conclusion?

We all know that HPS and LED lamps are probably the most efficient in terms of umols per watt, but HPS more so than LED generally falls short in the spectrum department. LEDs arent much better with very few off the shelf retail units that offer full spectrum, those that do are incredibly expensive and aren't as efficient or offer anything over other technology like CMH which is less than half the price of some LED units. LED units that offer mono-spectrum/dual spec like the best HPS do generally do have a higher umols per watt, but the cost per unit again is generally staggeringly expensive.

Over in the states we see a lot of growers using a mix of HPS and full spectrum lighting sources, which is a great idea as it's a way of delivering the PPF nice and cheap with the HPS whilst still getting that full spectrum goodness in there with LEDs/CMH/Plasma lighting.

Every kind of lighting will grow quality cannabis, there is no question in mind that full spectrum lighting grows better weed than mono-spectrum lighting does, however we were all very content with mono spectrum weed for a very long, it's not bad stuff infact it's great stuff - we can just do better

When it comes to lighting there is unfortunately no silver bullet unit that is going to give us the best efficiency of any lamp with full spectrum. IMO if we're wanting the highest PPFD and the biggest yield from the least amount of lighting units then the way to go is either 400v 600w HPS or 1000w DE HPS. If we're home hobby growers who want efficiency in our lamps,full spectrum and still get good yields then the CMH is the way to go and maybe LED in the future if the price ever becomes more sensible, and obviously if we're wanting the best of both worlds then its obvious we've got to mix HPS with CMH/LED.

Hope this helps anyone who is looking into lighting make a more informed choice

Edited August 7, 2016 by Golden Syrup

[GreenVision]

@@Golden Syrup There is nothing here I disagree with mate. The figures (as long as not given by some company trying it on) don't lie.

But as I have been reading quite a bit recently I have discovered that for me personally there is more to choosing a light than "Light"..

There are other factors involved in choosing a light. As one chap might say they want "Basic" HPS because they're great, give excellent results and cost a laughable 5% of LED units, the next chap might say the want less fire fire risk, or more distance from plant tops, less consumption..

What I ended up telling myself after weeks of numbers, youtube videos, emails etc etc is that if I could choose any of the setups I have to choose from for FREE which would I choose and why. Take the initial sting of purchase price out of the equation and go from there. I then wound up asking myself a different row of questions rather than the age old "Which is more powerful for my £££'s".

Once I started looking a different factors rather than Lumens, PAR & UMOLS I started to discover there is more to a light unit than I thought..

GV.

Edited August 7, 2016 by GreenVision

[GSZZ]

@@GreenVision

If money isn't a consideration then what you're saying is absolutely spot on, however I don't personally feel you can factor in consumption and then not the price of the unit, or the PPF as these are all linked to one another in making an informed choice which is what this is all about, the saving on electrics offsets the price of the unit, and there is no point in any of that if the PPF isn't the same or more as what we're currently using otherwise we're looking at a loss in yield.

With the exception of your point on fire hazard, less consumption from LEDs doesn't offset the price of the unit as quickly as other technology does thats what less consumption is about, paying less of the electric bill and there is no point in that if the units has cost thousands of pounds.

As for more distance between the unit and plants, you can do that with any lighting source that all comes down to PPFD too, as the higher the unit the more spread across an area the PPF is and thus lower the PPFD. With unit costs into consideration (because lets be real, we've got to factor in the unit costs otherwise we're not making an informed choice, and if we're not doing that then why are we doing it?) in most examples it would work out better to just raise existing lamps and then add another, as it'll still work out better over all to pay the extra bit on the electric per month than spend thousands of pounds of units so you can hang them higher... it might take 10 years or something for the extra cost of the electricity bill to add up to what it would've cost to buy X amount of LED units.

I'm not taking a bash at LEDs here I've repeatedly said that they work, you can grow really nice weed under them as I've smoked plenty but in nearly all of cases they just aren't very efficient because of the really high unit costs.

[Devcal]

@@Golden Syrup fantastic idea for a thread mate, very useful bringing a lot of bits of info together in one place and answering some questions that seem to pop up repeatedly. Good one taking the time to lay it all out

My experience over the last 6 months using a 630 watt Dimlux fixture in-between two 400v DE sodiums (running at 600 watts in a 2.4x1.2m) tent have been pretty pleasing, its hard to commit on the individual plants as most are from seed however I have noticed all the plants are drinking about 20% more water throughout flower than without the ceramic in....visually they look pretty happy too, these are about 10 days into 12/12 sitting right under the ceramic.

[GreenVision]

@@Golden Syrup Your first line is 100% correct again mate. If you ignore Price then you must therefore ignore consumption too as you cant deduct the savings in consumption.

But electricity consumption isn't just about the price I pay for leccy, its the KW hours that get recorded too.. I didn't want to mention this on UK420 as any time we talk about negatives within growing detection its called scare mongering. But I recently had a phone call from my new energy supplier at the new Gaff. They wanted to get me on a better tarrif, but a few mins into the cal the chap asked for meter readings. Once all said and done he did a calculation then started asking some "Odd" questions.

I have always played the game like I don't give a shit about getting caught, but anything I can help to avoid it I will.. Its scared me enough to know I need to drop my wattage. If LED's can offer the same yield for 400w less then I have to say to myself that i just cant put a price on even the slightest bit of extra security..

Then there is these newer smart meters. We have already had the letter about it from them.

As I say mate, the decision isn't a straight forward one. Once I am in full veg I am running 3 600w or 4 400w MH bulbs for 18 hours a day!!.. Its literally sending my leccy meter AWOL.

[GSZZ]

@@GreenVision

Whilst I don't agree entirely with the risk of using electric you make some very valid points that should be in the thread for anyone who DOES have those sort of concerns. But bare in mind if you're matching PPFD like you said you might save 400w~ of eletricity off the kWh but the leccy meter is still going to spin like crazy mate it's just the nature of the beast esp in big spaces. A watts a watt as they say and LEDs aren't that much more efficient than traditional and newer lighting! But any leccy off the meter in that respect is a good thing

@@Devcal

Great to see plants under that pleasing full spectrum I noticed that they started drinking a lot more under the ceramics/full spectrum too! On average in the height of flower I tend to have to change the 200L butt once every 4 days! Your set up is a great example of mixing lighting to get the best results!

Edited August 7, 2016 by Golden Syrup

[GreenVision]

@@GreenVision

Whilst I don't agree entirely with the risk of using electric you make some very valid points that should be in the thread for anyone who DOES have those sort of concerns. But bare in mind if you're matching PPFD like you said you might save 400w~ of eletricity off the kWh but the leccy meter is still going to spin like crazy mate it's just the nature of the beast esp in big spaces. A watts a watt as they say and LEDs aren't that much more efficient than traditional and newer lighting! But any leccy off the meter in that respect is a good thing

I have to be honest and say its my main goal when I change my lighting. I want to achieve the same good yield with less watts running.. And with my hand on my heart I don't care what setup does it... ..

I don't go in for great looking gear roll with the tide / wagon for the sake of it.. I'm the only one that ever sees my grows. But I know its possible to make my grow more effective where the watts are concerned. I struggle a little with the CMH I think because of the odd wattage numbers.. I see 315w and its rattles my feathers a little.. TBH I dont really know how to compare them in the grow area.

[Devcal]

@@Devcal

Great to see plants under that pleasing full spectrum I noticed that they started drinking a lot more under the ceramics/full spectrum too! On average in the height of flower I tend to have to change the 200L butt once every 4 days! Your set up is a great example of mixing lighting to get the best results!

Cheers mate, once funds allow I will be swapping one of the sodiums for another Dimlux I think, and I'll probably stick a Maxi unit in the veg room rather than the MH's

[SkyRider]

I have dabbled a little with HPS, LED and CMH. I have grown the majority of my ganja under HPS. No bigger than 600W. I have done a couple of grows under LED (around 600W draw). Maybe 5? Perhaps 6... I have done a single grow under CMH.

I can't comment at all on yield. I have a feeling the CMH once tuned in will out yield the other technologies, but that is just a feeling. I'm sure that better HPS systems than what I used might be able to beat it.

The one thing I am sure on though is effect. In the war with HPS and LED I always believed that HPS would out yield LED and to get anywhere close to the same yields with LED you would need to spend big. Now whether that is true or not to me was irrelevant. LED produced nicer tasting weed. Hands done. Maybe that is to do with heat as others have suggested to me, or maybe it is down to the different light spectrum. Whatever, it was certainly very noticeable in the end product. When I was running a HPS and LED flower tent at the same time, it was always the LED weed that I went for first.

Now after a single harvest under purely CMH I am amazed. The taste is there. As strong as LED weed. I can't yet work out if the taste is more defined or not. But the "hit" feels stronger. That then leads on to a much, much stronger high. In short, it feels like this weed is something different to what I have smoked before. I've just harvested 17 plants on the hunt for keepers and I've probably tried around half of them so far. Each and every one is smoking like a keeper. I haven't found a bad smoke in the lot yet!

Now that is just my experience and it's not very scientific. I haven't done any direct comparisons but to me I won't be looking toward any other light technologies for the near future. Have been holding back from going completely over to CMH but this week my veg cupboard will be changing over too

HPS = normal

LED = super tasty

CMH = super tasty and a hell of a hit

[zero]

years ago I did a fair bit of research on this (forgotten most of it now) , anyhow , I came to the realization that that the best way to measure efficiency (not spectrums or anything) was a ratio between lumens and heat ... all light produces heat and the more lumens the more heat , heat is a by product for growers , so the light that produces more lumens for less heat is the most efficient .... unfortunately lights arent measured in this way so its purely academic

[GSZZ]

@@SkyRider

Yep! The difference is huge between HPS V CMH/ Full spectrum cannabis, someone here mentioned it that HPS weed is "flat" which I think is a better word than bland, compared to full spectrum weed. The heat thing definitely plays a part as we know some terpenes evaporate over certain temps, but the full spectrum makes for some much tastier and more potent weed. I get bored smoking the same cut under sodium but not under full spectrum!

[lazi]

Over a decade ago I used to frequent some North American sites.

One guy was proud of the fact that he had spent $25k testing bulbs but just what is the point of that? If we pick a standard, say 600w hps, which is the best lamp? Whatever the answer, there is a good chance that the answer is wrong next year. iow, the worst 600w hps lamp of today is probably better than the very best 600w hps from 18 months ago.

I know par and umols etc have their place but for comparing yesteryear with today, all we have is lumens. I remember a 400w hps being 40k lumens circa 2003. A few years ago a 400w hps was 55k lumens. Might well be more now.

Like many I love the new cmh. Won't surprise me if LEDs beat the shit out them in 10 years time...but not today punk...

[~Sanctuary~]

@@lazi Lumens aren't a barometer of how good a lamp is for growing, they are used to measure what we see as brightness from a lightbulb.

Umol, micromoles or par is a measurement of light energy a plant can receive and use, the measurement of light photons for plant growth I'm sure isn't a new thing.

Between the very best and worst there is only a small percentage of performance difference for most hps, Lumateks 600w dual spec is 90 or so umol down from gavitas for example and both haven't developed or changed their bulbs since release.

Just as likely to have the same plus on negative impacts as the extra par from a lamp are light intensity throughout the growing cycle, environmental control, wall reflectivity, reflector performance, replacement or cleaning of reflective surfaces etc.

Edited August 18, 2016 by ~Sanctuary~

[botanics]

@@Golden Syrup

Good thread this dude

Been reading up on some chaps' techniques elsewhere and it seems that the addition of the UVB is a huge factor in the quantity of trichomes, flavour wise though I don't know the relation but I'm thinking of sticking a couple of UVB lamps in (I've read about 10 to 15 % of total lighting for the UVB) after noticing after using standard Halide during my last run for the first time, that flavours were improved and more frostiness, but could be genetics too so need a few runs of different strains before judgement (I ran Halide until the stretch was done 7200K and then switched to sodium dual spec until the last couple of weeks when I switched back to the halide to finish off).

When I get around to it, I'll report in

[GSZZ]

@@botanics

Adding UVB lamps beyond adding lamps that have got high UV anyway (MH/CMH) it's beyond my experience! Please do let us know how you get on In theory you could apply as much UVB as some unique parts of the world that would add a proper truly trippy effect to the weed I imagine