Bad News About LED vs HPS

[InTheValley]

humm cookie master, realllly???

and i agree on Los Reefer suggfest the thread independent. nice to

 

[CobKits]

your temps are probably too low

 

[mauricem00]

The plants have never looked healthier than they do under the 1/2 minus green HPS. The leaves are perfectly green all over, meaning no signs of burning or bleaching. My wattage now is the 150w HPS with two 14w LED bulbs on top, to fill in the ends and provide more blue (5000k), and two on the bottom pointing upward to prevent dark zones. So 206w altogether. With the filter, the HPS output may be reduced to a little over 100w of light. So still probably about 160w worth of light in a 3"x 1.5" area. No signs of too little light, buds are looking normal. I think I was using way too much light before. The water usage is also down considerably.

Actually the reduced water transpiration may be preventing nute burn. The more water gets pulled up to cool the leaves, the more nutes are pulled up with it. Which is something to think about when choosing circulation fans or when using high wattages of light.

I'm curious. what kind of yields are you getting with a 150 watt HPS I have a 6ft by 2 ft flowering closet and am thinking about adding a 150 watt hps next to my 4 ft T5 fixture in that closet.so I can add one more plant.2 ft T5s on the market have low quality ballast with B.Fs around 0.82. and this looks like an affordable option to fill that space next to my T5s https://www.amazon.com/dp/B01KMW7RYM/_encoding=UTF8?coliid=I16MXY1M60S5MV&colid=AW7UKM9ED6GM after searching you tube videos I found that even with high end LEDs some strains do not flower and those that do produce about 0.45 GPW. and that is using lights that cost $800-$1200. this HPS uses an enhanced spectrum horticultural bulb ( a little more blue).in this closet the extra plant would ged some light from the T5 but most from the HPS

 

[BobCajun]

I actually just started using them, due to burnout problems with LEDs and drivers, so don't know yet, and it's not pure HPS anyway because I added some LED "lightbulbs". Sorry I can't help you on that. But a 150 would be about right for the 2'x2' area in the end as you mentioned. BTW, when you screw the bulb in it's probably good to position it so that the metal rod that goes from one end of the arc tube to the other is angled upward or right at the top rather than on the bottom because it can block some of the light, being almost as wide as the arc itself. Kind of a bad design feature but I guess no way around it. I put it so it's not right at the top because most heat goes straight up and might make the rod very hot, which is probably not good.

 

[Johnny Lawrence]

after searching you tube videos I found that even with high end LEDs some strains do not flower and those that do produce about 0.45 GPW. and that is using lights that cost $800-$1200.

I'm sorry, what???

 

[mauricem00]

thanks maurice that was super informative i didnt realize the huge discrepancy in T5 efficiency and agree that any one built as a grow light uses the cheapest shoddiest bulbs and ballasts

i was looking more closely at the CMH numbers, my cmh ballasts (hydrofarm) dont draw 355W from the wall, more like 335-340W at the wall, and is a square wave output which makes the output more efficient. on a bulb basis alone, the cmhs are almost 110 lm/W initally and maintain 95% of this after 2 full years of flowering. with a ballast around 93% efficient youre up around 99 lm/W of high-cri light at mean bulb life after 1 year of use

View attachment 3992841


i was digging a bit into GEs product data, and while i do see bulbs that are 4800 lumens that is initial not mean. traditionally fluorescents drop off steeply and then hold (as opposed to CMHs which are more linear). So the 4400 lumen mean data GE provides is probably more accurate. i dont know if the programmed start ballasts help with this lumen maintenance issues

View attachment 3992866



so using the 4400 mean lumens it seems that CMH and the best T5 are right in the same wheelhouse

Whether lumens translates into usable PAR is another story. CMH has lots of green light but the spectrum is more uniform than T5 with a green peak centered wright where lumens are measured. also worth consideration with the "green inhibition" noted in this thread

would be a good side by side of one of the more efficient T5 setups vs a 315. what do those HQ bulbs and ballasts cost typically?

obviously DE HPS and LED with system efficiencies of 130-160+ lm/W are in a class of their own

that HQ T5 info should get out there. easy retrofit of ballast and bulbs into the shit ton of fixtures out there, and the spectrum of fluorescent (and mellow uniform lighting) is a proven performer for rooting and early veg

there seems to be somethign about the CMH spectra though. As ive mentioned ive seen people hit 1.4 GPW with rooms of 315s, ive never seen that with T5s (ive also never seen anyone using those super efficient T5s

heres a link (a few years old) where GE claims the T8 is even better (pg 23). im sure this info is somewhat dated

https://ewh.ieee.org/r3/atlanta/ias/Whats New in Lighting w_ LED.pdf

https://www.1000bulbs.com/product/89342/FHO-49T5850.html mean lumen on these bulbs is 4625 and dropoff in no where near as fast as HIDs https://www.1000bulbs.com/product/91988/PLUSRITE-7318.html https://www.1000bulbs.com/product/91989/PLUSRITE-7319.html commercial quality bulbs and ballast do not have the price mark up we see and specialty stores or even the markup seen at home depot. I have money. I just don't like to waste it. many self made men treat the book " millionaire next door" almost as a bible and are proud of how fugal they can be.once I got into a discussion with some small business men who all had a net worth over $1000000 where people were proud about how old their appliances were or the fact that they drive their cars till the wheels fall off. for them money is just a tool for making more money.I'm 60 years old and retired but due to recient good fortune my income has increased by $30,000/year bringing me up to $100,000/year for sitting on my ass doing nothing. work my ass off all my life to get here but I still look for bargains and hate paying more than I need too. all forms of lighting have improved over time and the bulbs and ballast listed were developed for commercial applications. you may not find them at home depot but technology does not take long to become obsolete. in your proposed comparison grow I would bet on the cmh by a slight margin but it would be interesting.cheap Chinese led grow light makers are not the only ones who try to take advantage of us "dumb" cannabis growers

 

[Johnny Lawrence]

And small HID bulbs are really inefficient.

 

[cookie master]

by inefficient you mean you dont get a lb off a 250 watt right? but you can get an lb off a 400. Im being a dick by being argumentative but 315 is a small hid bulb.

 

[CobKits]

And small HID bulbs are really inefficient.

this

anything less than 600 DE really isnt even in the mix these days as far as hps

 

[mauricem00]

I actually just started using them, due to burnout problems with LEDs and drivers, so don't know yet, and it's not pure HPS anyway because I added some LED "lightbulbs". Sorry I can't help you on that. But a 150 would be about right for the 2'x2' area in the end as you mentioned. BTW, when you screw the bulb in it's probably good to position it so that the metal rod that goes from one end of the arc tube to the other is angled upward or right at the top rather than on the bottom because it can block some of the light, being almost as wide as the arc itself. Kind of a bad design feature but I guess no way around it. I put it so it's not right at the top because most heat goes straight up and might make the rod very hot, which is probably not good.

thank you. for $60 it's not much of a gamble and looks like a better option than anything else in that price range.also a good ideal to wear gloves when handling bulbs and wipe them down with a clean cloth to keep oil from your fingers getting on them which could cause them to explode

 

[cookie master]

he said hid, not hps. And I still like hps, I sometimes have plants 10 inches away from a 1000 due to height constraints.

 

[Johnny Lawrence]

by inefficient you mean you dont get a lb off a 250 watt right?

Ummmm, no, I mean that they're inefficient. Do you understand what the word means?

but you can get an lb off a 400. Im being a dick by being argumentative but 315 is a small hid bulb.

Ceramics are different than MH and HPS

 

[Rahz]

I found that even with high end LEDs some strains do not flower and those that do produce about 0.45 GPW. and that is using lights that cost $800-$1200.

There might be some Chinese LED grow lights that will only provide .45 GPW, but if by high end you mean high efficiency phosphor based LED you can expect 1.25-1.75 GPW depending on strain and growing method. I was pulling those numbers years ago using DIY lamps I wouldn't even sell now because the efficiency was under 50%.

Lamp 1- Vero 18 g5 @ 1050ma. My estimates suggest 35% efficiency. 700 output watts over 18 square feet. 700*.35= 245 PAR watts. 13.6 par watts per foot. Grown in hydro, yield was between 1.1 and 1.2 GPW from the wall. Best yield was over 2lb.

Average grams per par watt = 3.28

Lamp 2- Vero 29 g5 @ 700ma. My estimates suggest 42% efficiency. 350 output watts over 10 square feet. 350*.42= 147 PAR watts. 14.7 par watts per foot. Grown in hydro yield was between 1.4 and 1.57 GPW from the wall. Best yield was 21 zips.

Average grams per par watt = 3.57

I understand the efficiency argument has gotten old, but beyond that and the amount of energy we're throwing on the canopy we're really picking the bones talking about spectrum. Not that I think spectrum shouldn't be discussed but the difference a spectrum will make is a small slice of the pie. I know first hand the difference between CFL and 35% LED. LED won big time. Nothing else was changed, not even the strain. It was simply a switch out 600w of T5 for 700w of LED. Last fluorescent grow was 17 zips, first LED grow was 28 zips. Difference being the PAR wattage went up and the light that was being reflected before hitting the canopy went down. Even if we scale the LED down to 600w it would have been 24 zips. And that was under what I would consider a low efficiency LED by today's standards. I grew many times with those fluorescent bulbs and never got anywhere close to 24 zips.

Going by PAR watts alone I should have been getting at least 21 zips from the 600w of T5s, but I didn't. The reason probably wasn't spectrum, it's the fact that half the light had to hit a reflector before being directed to the canopy. That's the only reason I can think of for why my GPPW went up when switching to LED. That will also be true for other bulbs unless used vertically.

 

[BobCajun]

There might be some Chinese LED grow lights that will only provide .45 GPW, but if by high end you mean high efficiency phosphor based LED you can expect 1.25-1.75 GPW depending on strain and growing method. I was pulling those numbers years ago using DIY lamps I wouldn't even sell because the efficiency was under 50%.

Lamp 1- Vero 18 g5 @ 1050ma. My estimates suggest 35% efficiency. 700 output watts over 18 square feet. 700*.35= 245 PAR watts. 13.6 par watts per foot. Grown in hydro, yield was between 1.1 and 1.2 GPW from the wall. Best yield was over 2lb.

Average grams per par watt = 3.28

Lamp 2- Vero 29 g5 @ 700ma. My estimates suggest 42% efficiency. 350 output watts over 10 square feet. 350*.42= 147 PAR watts. 14.7 par watts per foot. Grown in hydro yield was between 1.4 and 1.57 GPW from the wall. Best yield was 21 zips.

Average grams per par watt = 3.57

I understand the efficiency argument has gotten old, but beyond that and the amount of energy we're throwing on the canopy we're really picking the bones talking about spectrum. Not that I think spectrum shouldn't be discussed but the difference a spectrum will make is a small slice of the pie. I know first hand the difference between CFL and 35% LED. LED won big time. Nothing else was changed, not even the strain. It was simply a switch out 600w of T5 for 700w of LED. Last fluorescent grow was 17 zips, first LED grow was 28 zips. Difference being the PAR wattage went up and the light that was being reflected before hitting the canopy went down. Even if we scale the LED down to 600w it would have been 24 zips. And that was under what I would consider a low efficiency LED by today's standards. I grew many times with those fluorescent bulbs and never got anywhere close to 24 zips.

Going by PAR watts alone I should have been getting at least 21 zips from the 600w of T5s, but I didn't. The reason probably wasn't spectrum, it's the fact that half the light had to hit a reflector before being directed to the canopy. That's the only reason I can think of for why my GPPW went up when switching to LED. That will also be true for other bulbs unless used vertically.

LEDs do have reflectors though, the back of the LED is reflectorized. Half the light presumably does bounce off that. I think much of the difference may be that LEDs run on DC so it's on steady rather than flickering on and off at house current frequency. An article about pulsed light mentioned than many light meters can't accurately read flickering light. The actual amount of light received by the plants could be considerably different than what the meter would indicate.

 

[Rahz]

LEDs can be fitted with reflectors but the back of the LED isn't reflectorized. Individual diodes are often fitted with tiny cone reflectors and/or lenses but this isn't true of cobs. Photons tend to leave the junction at 90 degrees from the junction surface but there is a potential 180 degree pattern.



In my case no reflectors were used. I ran cobs at 30 watts or less in an hexagonal pattern and kept the lamp 4-6" or less from the canopy during flowering. The last couple grows I was allowing the plants to grow up through the frame. I wish I had taken pictures of it.

Generally speaking cob LED should never need to be more than 14-16 above the canopy to minimize reflective loss. If someone is using cobs with 90 degree reflectors or lenses and has their lamp higher than that they're missing out.

 

[OneHitDone]

LEDs do have reflectors though, the back of the LED is reflectorized. Half the light presumably does bounce off that. I think much of the difference may be that LEDs run on DC so it's on steady rather than flickering on and off at house current frequency. An article about pulsed light mentioned than many light meters can't accurately read flickering light. The actual amount of light received by the plants could be considerably different than what the meter would indicate.

I believe the only HID operating at 60hz would be magnetic ballasts?

 

[nfhiggs]

im just vegging, and cloning. I just switched the other half of the lec on for 630 watts but it was doing fine for babies. But for some reason the ones under cobs always seem stalled for 2 or 3 times ive vegged under it now.. They dont really drink and just sit still/ and tend to go pale or turn purple in veg. Almost like nute deficiency but they arent drinking and they are babies so im not gonna pump them. Under hps or lec they grow fast, look perky, and need watering more.

Temps....

 

[BobCajun]

LEDs can be fitted with reflectors but the back of the LED isn't reflectorized. Individual diodes are often fitted with tiny cone reflectors and/or lenses but this isn't true of cobs. Photons tend to leave the junction at 90 degrees from the junction surface but there is a potential 180 degree pattern.

View attachment 3993021

In my case no reflectors were used. I ran cobs at 30 watts or less in an hexagonal pattern and kept the lamp 4-6" or less from the canopy during flowering. The last couple grows I was allowing the plants to grow up through the frame. I wish I had taken pictures of it.

Generally speaking cob LED should never need to be more than 14-16 above the canopy to minimize reflective loss. If someone is using cobs with 90 degree reflectors or lenses and has their lamp higher than that they're missing out.

I guess you're right about no builtin reflectors in LEDs. Thought I read that somewhere but can't seem to find it anywhere now so obviously not a commonly reported part of LEDs. All I found was that about half the light just gets absorbed back into the LED and is the main cause of the heat. Got that from https://en.wikipedia.org/wiki/Light_extraction_in_LEDs. The light doesn't come out at 90 degrees though, meaning straight out, usually 120 beam angle.

From the rest of your post I see that my idea of less current but LEDs only about 6" from the canopy seems to be valid. As you said, the higher up, the more reflection, and photon collisions resulting in light loss by conversion to heat. You would actually want the light going as straight down as possible, so no reflectors and actually no COBs but instead individual mid power LEDs spread out.

I would also recommend having some of them pointing upward from pot level, because you really can't get much penetration from any artificial light source. When I turn my bottom lights off it's quite dark down there. It makes a world of difference, a bunch of dark compared to light everywhere. It doesn't even take that much bottom light to dispel the darkness. I 've got about 6w /sq ft down there, just two 14w bulbs, three was making too much heat for my liking and two seems to suffice.

 

[BobCajun]

I believe the only HID operating at 60hz would be magnetic ballasts?

True, the electronic ballasts raise it to several kHz, which is why they give off so much microwave interference, which then prompts the cable companies to come see what's causing everybody in the neighborhood's cable TV to be screwed up and trace it right to you. But I digress. It's still not steady light, as far as I know, just looks smoother to the eye. I don't know if flicker makes light less efficient for growing, it's just a hunch I had, trying to explain why LED seems to yield so much more than HPS of equal wattage. May have nothing to do with the power supply.

 

[ZeroTrousers]

True, the electronic ballasts raise it to several kHz, which is why they give off so much microwave interference, which then prompts the cable companies to come see what's causing everybody in the neighborhood's cable TV to be screwed up and trace it right to you. But I digress. It's still not steady light, as far as I know, just looks smoother to the eye. I don't know if flicker makes light less efficient for growing, it's just a hunch I had, trying to explain why LED seems to yield so much more than HPS of equal wattage. May have nothing to do with the power supply.

LED yields more at equal wattage because a decent LED produces more useable photons per watt. It has nothing to do with pulsed output.

The because even the best HPS is only ~30% efficient at converting watts to photons.

Average LED is something like 40-47% efficient if properly cooled, the best LED can edge towards 55-59% when under-driven. There's also the argument that more light from LED is usable, but I'm not wholly convinced yet.