note: This thread was some of my first research work since I joined GC. There is a sister thread I just started with lots more recent research here: http://forum.grasscity.com/absolute-beginners/529078-how-light-works-tackling-question.html I will try to maintain both threads as best as I can... (01/11/2010) So I was thinking about getting rid of my ugly array of CFL lights and using ONE small HID light for better penetration. I currently have 188Watts of CFL light, which ammounts to 12000 Lumens. I was going to switch to a 150W HPS... I figured I'd get less lumens but better penetration. I did a BUNCH of research and thinking, and changed my mind... I'm sharing it here now to save others time and confusion so I hope this helps somebody... Also I'm definitely not a genius so if I've calculated way wrong please feel free to call me out on this... Like I said, I've currently got 188watts of CFL dispensing 12,000 Lumens, which comes out to 61 lumens/watt if you count 10watts worth of pc fans to keep them cool. My area is about 4square feet, so at 3,000Lumens per square foot, this is a good place to be in. According to specs, the 150Watt HPS bulb delivers 15,000 Lumens of light. At face value you'd think that means it's efficiency is about 100Lumens/Watt, but us stoners are smarter than that right? What they won't tell you is that the 150Watts is the power being drawn by the bulb. There is an electrical loss (as you'd expect) inside the ballast which is reflected in the form of additional current drop. (inductors and capacitors present "reactance" [ac resistance], blah blah blah, been too long since I went to school for some of this...) Anyway, if you read the spec sheet for the 150 watt ballast (based on info from 1000bulbs.com) it will tell you that the operating current of the ballast (NOT the open or starting current) is 1.65 amps at 120V AC... If you plug this into a units converter, it will tell you that the actual power being used by the lamp is 199Watts while it is on. This brings you down from the 100lumens/watt efficiency you thought you had to an actual efficiency figure of 76 Lumens per watt ACTUAL efficiency. Although 76 Lumens per watt is better than the 61Lumens I'm seeing now, that's only 15lumens per watt more than I'm getting now. Let's make the comparison for the sake of example in terms of real power usage veses output: 199 Watts of power used (on a 150w HPS) yields 15,000 Lumens 208 Watts of CFL used (26W bulbs times 8 Is the closest you'll get) Yields 13,600 Lumens (1,700 Lumens per bulb) Do the subtraction and for the same ammount of power used, the 150W HPS Lamp is only ahead by 1,400 Lumens. That's LESS THAN ONE EXTRA CFL BULB! So how much bigger do you have to make the HPS lamp before it starts kicking CFL's ass in terms of power efficiency? Below you will find I have done the math for the popular sizes of High Pressure Sodium bulbs: 70w(90Watts actual)- 6000Lumen 67Lumen/Watt 100w(124Watts actual)- 9500Lumen 76Lumen/Watt 150w(199Watts actual)- 15000Lumen 76Lumen/Watt 250w(300Watts actual)- 29000Lumen 97Lumen/Watt 400w(468Watts actual)- 50000Lumen 107Lumen/Watt 600w(660Watts actual)- 90000Lumen 136Lumen/Watt 1000w(1140Watts actual)- 140000Lumen 140Lumen/Watt As you can see, the efficiency doesn't start to get worthwhile until you get up into the 250W-400W+ range. So I guess you could argue that CFL is the obvious choice for someone who wants to stay under 250 watts... So, are you bummed out because you think $60-$100 bucks for one of those huge 150watt cfl lights is unfair? So do I. The GOOD news is that in terms of light output per watt, the smaller CFL bulbs are more efficient than their larger counterparts. See the enclosed data below CFL Chart 26W- 1700Lumen 65Lumen/Watt 42W- 2600Lumen 62Lumen/Watt 65W- 3400Lumen 52Lumen/Watt 85W- 4200Lumen 49Lumen/Watt 105W- 6900Lumen 66Lumen/Watt 150W- 8200Lumen 55Lumen/Watt 200W- 10000Lumen 50Lumen/Watt Although it's not a huge difference, you can see that CFL bulbs show a general trend of decreased efficiency as they grow larger in size. What this means to us CFL nuts out there is that for about 25 bucks you can get a couple 3-packs of 26 watt CFLs (2700k of course). You'll use 156Watts and pump out 10,200 Lumens. That's 2,000 Lumens more than you get with that expensive big 150W bulb. Not to mention you can replace the bulbs individually if they burn out (for cheap), and did I mention that they run pretty cool? The 150W monster CFL runs WARM-hot... Now granted you'll have to rig up your own reflector hood or whatever, but stop and think about this for a second- the grow sights want an extra $65-$100 bucks for the reflector/wing thing for those huge 150Watt cfl bulbs anyway. For half that or less you can rig up your own with a bathroom vanity fixture and some Y-splitters, or some of those jobsite clamp lamp things with the aluminum reflector dome built in. So that's it... If you've made it to the end of this post then I thank you for your time. Basically the moral here is don't bother with small HID lights... If you're going to stay under 250Watts then just do CFL, and don't you dare waste your money on one of those huge 150Watt CFLs- get a bunch of smaller bulbs for cheaper, with better heat control, more lumens/watt, and more versatility for distributing your light. CHEERS!
very nice post Ive noticed an advantage to both though Use CFLs (266 watts) for veg (130 watts 2700k (5 x 26 watt) and 136 watts 6500k ( 2 x 26 + 2 x 42)). Total lumens -= 17,100 / 266 watts = 64 lumens / watt. at flowering ADD 150w HPS (16000 lumens) and subtract 78watts 2700k cfl. Total lumens = 28,000 lumens / 387 watts (using your 199 watts figure for ballast) = 72 lumens/watt. advantage comes from you get all the power of a 250w HPS with 28,000 lumens, BUT when your plants are young, you can use considerably less light (cfls only). with a small number of plants, in a small space, a YOUNG plant cant tell the difference in 16000 and 30000 lumens, but the same plant in flower phase most certainly could at first, only use 100w of cfl, after a week turn it up a little, until you add the HID at flower. the saved power over the first few weeks will add up tremendously Your plants wont even stretch when you switch to flower, so maybe thats a reason to even advocate using cfl THEN adding HID...or at least increase lumens when you go to 12/12
I use a combination of both,...it works the best I have seen so far. I use 150 watt hps, 4-27 watts 6500k cfl's and one 65-watt 6500k cfl fixture... I knew heat was gonna be an issue so I made a little cooltube for the hps....I love my veg box...
Amoril- I like your idea of starting with cfl when the plants are small and moving to HID later to save money. Please don't take this personally because you can clearly afford more juice than I can, but why not try this: Forget the 150W hps, Get a 250W hps. Use only cfl lights for vegg and maybe early flower like you said you do anyway. When you get to the point where you would use your cfl and 150W hps, remove ALL CFL and switch to 250W HPS. Remember 250W HPS- (300W actual), 29,000 Lumens, 97Lumens/Watt Verses your mix which weighs in as follows 387watts 28,000 Lumens, 72 Lumens/Watt If you just used the HID, you'll get an extra 1,000 lumens and use almost 100 watts less power. Don't get me wrong, CFL are great, espescially for side lighting and their low heat etc. Hell, they're all I can afford, but I guess this sort of proves my point: If efficiency/cost are your only concern, cfls lose their bennefit unless you're running around 200W of light or less overall. Also people should note that HPS lights 150W or less aren't anywhere near as light efficient as their big cousins. Again don't get me wrong, I'll admit i never tried one and can't afford one. Also HID (HPS) Light does penetrate the canopy better, but if they're going to have almost the same efficiency as CFL (in terms of lumens/watt) until you clear the 250W HPS hurdle, then I'd personally run CFL and distribute the light with good bulb placement. Food for thought anyway. CHEERS!
That's great info, thanks. Here's before shot of my small CFL box, I'll post current state of the grow later today, 28 days into veggin
Thanks man. Please feel free to link to this thread anytime it's relevant. It's not getting a lot of traffic and I don't want it to get closed. Thinking about asking an admin to move it over to "absolute beginners" It contains lots of basic calculations that I think would help newbies make a better informed decision on their lighting choice... Plus, this thread isn't pushing CFL as a solution overall, but I guess just trying to weight them out. I'll definitely admit HID is best- when you can use one to it's best potential and accomodate it's needs...
nice thread weasel! i think im going to be getting a 250 watt hps in the near future in place of my 220watts of cfls.
Please feel free to link to it from your posts before the thread gets closed. Also, anyone have any requests for info I could include? I'm thinking of trying to Include data for MH and T5-HO but it's still in the works...
great info man, I to use a combo of CFL for side lighting and a 150hps with a cooltube to top it off. works wonders!
I sat down and worked up the same chart as id did for the HPS, but this time for the MH lights. As you can see they're less efficient than the HPS lights across the board. Metal Halide 50W(72Watts actual)- 3200Lumen 44Lumen/Watt 70w(102Watts actual)- 5,000Lumen 49Lumen/Watt 100w(139Watts actual)- 7,700Lumen 55Lumen/Watt 150w(197Watts actual)- 11,000Lumen 56Lumen/Watt 175W(216Watts actual)- 12,800Lumen 59Lumen/Watt 250w(300Watts actual)- 20,000Lumen 67Lumen/Watt 400w(492Watts actual)- 36,000Lumen 73Lumen/Watt 1000w(1104Watts actual)- 110,000Lumen 100Lumen/Watt Here's the deal: if you compare metal halide against CFL, they're not much better if at all until you've got 400W or more going. At that point, I'd recommend just getting The 400W HPS instead since it puts out more lumens and is acceptable for vegitative growth as well as flowering. As for people looking to vegg their plants with less than 400watts? I'd say that CFL is your winner again...
Here at last, are the T5HO Statistics. Supposedly, most T5HO grow light setups use Universal AccuStart brand or Advance CentiumT5 brand ballasts. I was able to find data sheets for the Universal AccuStart, but not the Advance transformer ballast, but pretty much everything I was able to find for many other companies seemed to all have the same specs. Here are a few links from some of the easier to read sources: http://content.sylvania.com/app/display.aspx?id=003678759 http://www.unvlt.com/literature/brochures/t5ho_brochure.pdf http://www.unvlt.com/literature/flyers/t5_he.pdf 24w (28Watt actual) [22in long “2 foot” tubes] 2,000 Lumens, 71 Lumens/Watt 39w (45.5Watt actual) [34in long “3 foot” tubes] 3,500 Lumens, 77 Lumens/Watt 54w (60Watt actual) [46in long “4 foot” tubes] 5,000 Lumens, 83 Lumens/Watt Again you may find it confusing that I have listed two wattages for each lamp. If you’ve been reading along (I hope you made it this far J) you’ll know that the first figure is the wattage being drawn by the bulb. The second, slightly higher figure is the bulb plus the power consumed be the transformer inside. Or in other words, for the 2-foot tubes, the bulb is drawing 24 watts of power (from the transformer), but the combined system is drawing 28 watts as a whole. You’ll notice that my input wattages used for calculation purposes are slightly higher than the ones listed by the data sheet. This is because I did the calculations myself using (ohms law and) the input voltage and amperage figures they list on the data sheet. What I discovered? Even over something as petty as one watt, it appears they “fluffed” their statistics a little bit. You can use this basic model to figure out how much power a given fixture actually consumes. As for the efficiency, you can multiply it out yourself and it will come out the same as above. Or in other words, fixtures that use 2-foot tubes will produce about 71 Lumens for each watt of power used by the fixture. 3-foot systems will see about 77 Lumens/Watt. And 4-foot systems will see about 83 Lumens/Watt. Take for example this unit. http://www.plantlightinghydroponics...t4-lamp-t5-fluorescent-grow-light-p-1935.html Looks pretty straightforward. It’s got four 2-foot long T5HO tubes stuffed in there. They’re claiming that it’s 96Watts (24Watts each times 4). And in a sense they’re right. The bulbs draw 96 watts. The fixture doesn’t… It actually draws about 112 Watts altogether. The way the ad is presented, it leads you to believe you’re getting about 83 Lumens/Watt (8000Lumens/96Watts). In reality you’re getting more like 71 Lumens/Watt (8000Lumens/112Watts). Why does this matter? Because I’m trying to show you that T5HO fixtures cost so friggin’ much, IMHO you should either use CFL on grows weighing in at 300watts or less to save cash, or get a HPS if it’s going north of 300watts overall. Still not convinced? Let’s crunch some more numbers… I’ll compare the “96watt” (112Watts actual) fixture to its approximate CFL equivalent: 112Watt T5HO fixture-> 8,000 Lumens= 71Lumens/Watt VS. 110Watts of CFL light -> 6,900 Lumens= 63Lumens/Watt (two 42Watt bulbs@ 2,600 Lumens Each, and one 26Watt bulb @1,700 Lumens) Ok, admittedly, we’re a little behind here, but it reinforces my point. Just like with the Smaller HPS, you’re only behind by 1,100 lumens, which is less than a single bulb. Difference in efficiency is 8Lumens/Watt, which isn’t too bad. But at $130 for the T5HO, setting up something comparable with CFL should cost 60-70% less. ------------------------------------------------------------------------------------------------------------ Let’s dust off for round 2… We’ll start with this unit: http://www.plantlightinghydroponics...ens-3ft-t5-fluorescent-grow-light-p-2344.html Again, if you crunch the numbers, you’ll see this unit actually draws about 182Watts, not 156Watts. We’ll stack it up against the closest combination of CFL I can hack together… 182Watt T5HO Fixture-> 13,200 Lumens= 72Lumens/Watt (a little less than I predicted earlier, but it’s because they’re only declaring 3,300 lumens for each bulb, and not 3,500 like most other manufacturers) VS 182Watts of CFL (7 bulbs *26Watts each @ 1700 Lumens apiece)-> 11,900 Lumens= 65Lumens/Watt This time the gap is a little bigger, but still not enough to justify the extra expense in my book…Anyhow, CFL is only 1,300 Lumens behind T5HO, which is again less than one CFL bulb’s difference. The other big difference is the price- The T5HO has doubled in price @ $274. CFL’s on the other hand are still only about 12 bucks per 3-pack, from GE. ------------------------------------------------------------------------------------------------------------ Still there? Let’s turn the dial all the way up on the T5HO’s and see how we make out… We’ll Start with this Light: http://www.plantlightinghydroponics...ens-4ft-t5-fluorescent-grow-light-p-1153.html Again, we’ll go ahead and correct the wattage to the actual power consumption before we get started… 240Watt T5HO Fixture-> 20,000 Lumens= 83Lumens/Watt Vs. 240Watts of CFL light -> 15,400 Lumens= 64Lumens/Watt (two 42Watt bulbs@ 2,600 Lumens Each, and six 26Watt bulb @1,700 Lumens) At last, the T5HO finally delivers some performance worth my attention… But still it’s only a couple or three CFL bulbs difference. However at this point, it wouldn’t make sense to use CFL because a 250Watt HPS would take the cake in this situation. In fact, at $250 bucks for the T5HO, you can probably get the 250W HPS cheaper. See the comparison below and we’ll look at all 3 of them: 240Watt T5HO Fixture-> 20,000 Lumens= 83Lumens/Watt VS A CFL setup put together to match the lumens (not watts) of the 20,000 Lumen T5HO setup. This is to demonstrate the energy you’ll waste and the efficiency you’ll sacrifice trying to catch up to the T5HO at this point. 302Watts of CFL-> 19,600 Lumens= 65Lumens/Watt (ten 26Watt bulbs @ 1,700 lumens each, plus one 42Watt bulb @ 2,600 Lumens) VS 250w(300Watts actual)- 29,000Lumen 97Lumen/Watt So at last the T5HO comes out on top (where it claims to be all along). But at this point, IMHO it makes more sense to give up on the T5HO altogether. Think about it- first of all we can see it isn’t worth it to use CFL to try to catch up at this point: in order to produce close to the same amount of light, it has to use more power than the HPS and puts out less light than either of them. Taking it a step further, the 250W HPS only uses 60Watts power more than the T5HO fixture, and produces 9,000 more lumens. Even if you live where electricity is as high as 16cents/kilowatt hour, that’s still only an extra $3.50 a month over what you’d pay to run the T5HO on 12/12. With the 250W HPS, you’ll get 9,000 more lumens and better penetration. Plus, you’ll actually get the 97lumens/watt that the 4foot T5HO’s claim (BOGUS!) to deliver. So that’s pretty much it… As a general rule, I’d recommend you apply the following statements if you’re new to growing and don’t have a clue what any of this means. 1) If you’ve got 300 watts or more (in your budget on your electric bill) to spare on the lighting alone, then start with a 250W HPS and pick the biggest HPS you need/can afford from there. 2) If you can’t afford 300 watts or more on the electric bill each month, then screw the hype and do the best you can with CFL. They’re not actually the best, but in most cases they’re damn close, and for the cost they always win hands down. CHEERS!
this is an amazing number crunching thread! i went from about 3-4,000 lumens in cfl to over 10,000 with my 150w-hps but my cfls probably used at least 100w so my only real issue was the heat.. the light is enclosed but has no venting so it gets pretty hot..workin on that one
you can pop the plastic base of a cfl apart with a flathead screwdriver. drill extra vent holes in the plastic radomes and pop it back together. it's what i did.
I'd like to take a monent to thank nawmean for the insighful private message he sent me. For the bennefit of the GC community i've decided to post what he said here as well as what I replied. Original Message to me: I appreciate all of your hard work and calculations comparing the lighting systems. I'm considering a CFL, T5HO, or HPS setup, and still doing some research. There are a few things that I'd like you to consider in your calculations regarding lighting. You may have though of these things before. 1) The Inverse Square Law dictates light intensity in relation to distance (from the marijuana grow bible by jorge cervantes p165) E = L/D^2 (read as the intensity of light equals lumen output over the distance squared) T5 and HPS light fixtures hang over the plant at an adjustable height, yet fixed vertical position (fixed y axis). It seems that CFL's are more versatile and can get closer to the plant and therefore minimize the distance from light output to plant. However, 2) CFL's disburse light in a somewhat outward circular pattern and the outer rim of light is not directly facing the plant. The outer rim's light output is also blocked by the inner rim on the opposite side of the same CFL. (I'm starting to confuse myself, but think about a running track and the outer edge of the track is the outer surface of the CFL, and the inner edge of the track is the inner surface of the CFL). My reply: "Thanks for your response good points about lighting- feel free to add to thread. It's true that light intensity does become reduced as distance increases. CFL suffer from this slightly more because they aren't as intense as HID. they make up for it in the fact that they can be hung around the plant. most of the light that comes off a CFL is from the sides of the spiral. best way to us them is a 3 step process: 1) use clamp lights with "Y-adapters" (2 bulbs per socket) to hang over the tops of the plants 2) invest in the highest quality reflective material you can affotd and line your area with it 3) for the rest of your lights, hang your CFL at difference heights among the plants. vertically with NO reflector. this will let the most light possible off the bulb in all directions before it gets reflected by the walls..." All others please feel free to share thoughts or comments on my research. CHEERS!