HPS vs. LED Grow Lights — Which is Better for Growing Weed?

Blue brother

Well-Known Member
My lumen argument wasn’t bashing leds or you or anyone for that matter, someone posted and said you can add lumens up, I replied and said that’s not possible. That’s it, somehow in the process of explaining why, I’ve been put in the corner with the troll. Now getting posts from so many other people going on as if I’m saying hid is better than led, which it’s not! Multiple sources that deliver the same amount of photons to the canopy =BETTER. I agree with that, I’ve been saying that since the start of the thread
Thankyou @Rocket Soul for liking this post, I hope u don’t think my constant battle at explaining this is a dig at you, cause it’s not, at first I just tried to explain one thing I didn’t agree with that you said, I agreed on everything else and by the way the thread reads from the start you can see we are pretty much on exactly the same page. Somehow to people just reading the last couple of pages before commenting I come across as someone who is slating led tech, which is definitely not the case at all.
 

Kassiopeija

Well-Known Member
and said you can add lumens up, I replied and said that’s not possible.
it's possible as that is what is happening in nature. you take 2 flashlights now into a dark basement and partially overlap their cones, there you can see it will be brighter where it overlaps.
that definition you cited is very base and doesn't forbid to calculate an integral over both as in treating both as single incidents and combining the result or do an approximation.
I mean regardless of whatever metric you use you may find it logically that its the light density that's being calculated, with a higher density equating more brightness and its irrelevant in that regard from which direction or how many sources the light was derived.

as for the fixture height it's about minimum distance, equal spread...the 1000w HPS in a closed hood doesn't benefit from a close proximity but a rail LED can. But the rail also can be mounted up high if the room setup allows it why not? as long as mostly the leaves get hit and not the light flies out of the next window...

from @Samwell Seed Well :

see they are both up high at the ceiling
it's about canopy PPFD
 

Prawn Connery

Well-Known Member
Thanks mate
Mate, I'm sorry if it seems we're ganging up on you. We're just trying (all of us) to explain to you why lumens (and luminous flux) have no real place in this argument, as well as the rationale behind light movers.

HPS should not be written off so easily and there are cases where it can penetrate deeper than LED – but perhaps not for the reasons you are thinking.

HPS emits a lot of green light. Green light penetrates the epidermis of plants to activate chloroplasts deeper within the leaf cell structure. These chloroplasts do not get activated as much by red and blue light, which do not penetrate through the leaf as effectively. Far Red light also penetrates the epidermis more effectively than red and blue light, and HPS also emits more Far Red than typical CRI70/80 white-phosphor LEDs that use a 450nm blue pump and are used in most LED horticultural fixtures (but not ours). These LEDs typically have little to no Far Red. Warm coloured CRI90-95 LEDs (2700-3000K etc) however, do emit similar amounts of Far Red.

This is all going somewhere – trust me.

Now plants are green, right? That doesn't mean they don't use green light. On the contrary! They photosynthesise it more efficiently. My (personal) theory is that is the reason why leaves are green: because they reflect the most efficient and abundant spectrum into the lower canopy, where fewer photons of green light can have the same photosynthetic value as more photons of red and blue light (that do not activate as many chloroplasts in the leaf).

So HPS can penetrate further by proxy – it produces more green light (and more far red light than typical LEDs) which is reflected deeper into the canopy. That is something that I think LED growers sometimes forget.

There are other reasons why HPS still performs well.

For the last 40 or so years cannabis has been selectively grown and bred under HPS. So any particular plant that performed well under HPS was bred from over successive generations. This means that cannabis has been selectively bred to perform well under HPS for decades. That will likely change as LEDs take over.

Another reason HPS can perform well is that is inefficient. WHAT?!? Yes, it produces more infrared heat than LED (converts more energy to heat than light compared to LED), but metabolic warmth is needed by all living things to speed up the organic processes (chemical reactions) of life. LED grows can suffer when there is not enough warmth – and cannabis especially needs warmth to thrive – so sometimes it is a good idea to throw a HPS or CMH lamp into a LED grow to increase ambient temperatures in the grow room/area. We even tell growers to do this if their rooms are too cold over winter.

All up, it is actually very hard to beat a HPS grow for overall yield where all the correct parameters are adhered to. That means having the optimum number of plants in the optimum area under the optimum amount of light with optimum nutrients and training. For any given area that has all these "optimum" levels, HPS can yield on par with LED.

HOWEVER! HPS will need around 50% more energy to do it, and the quality will never equal a UVA-enhanced LED fixture because there is not enough blue, violet and UVA light of higher energy to stress the plant into producing higher levels of secondary metabolitee (ie: cannabinoids).

So give HPS its due, but don't forget that it is 60-year-old technology that has been surpassed by LED technology that is only getting cheaper and more efficient by the day. HPS really has nowhere else to improve. Double-ended HPS may be better than single-ended fixtures, but that's about as good as it gets – or is likley to ever get – now that the world is switching to LED technology over HIDs.
 

Prawn Connery

Well-Known Member
For those who have been paying attention, yes that is a woman in a pink wig in the photos I posted. But no, it is not me (I'm a guy – sorry fellas).

She is an awesome grower. And she loves my lights :bigjoint:
Pixie1.jpg
 

Blue brother

Well-Known Member
Mate, I'm sorry if it seems we're ganging up on you. We're just trying (all of us) to explain to you why lumens (and luminous flux) have no real place in this argument, as well as the rationale behind light movers.

HPS should not be written off so easily and there are cases where it can penetrate deeper than LED – but perhaps not for the reasons you are thinking.

HPS emits a lot of green light. Green light penetrates the epidermis of plants to activate chloroplasts deeper within the leaf cell structure. These chloroplasts do not get activated as much by red and blue light, which do not penetrate through the leaf as effectively. Far Red light also penetrates the epidermis more effectively than red and blue light, and HPS also emits more Far Red than typical CRI70/80 white-phosphor LEDs that use a 450nm blue pump and are used in most LED horticultural fixtures (but not ours). These LEDs typically have little to no Far Red. Warm coloured CRI90-95 LEDs (2700-3000K etc) however, do emit similar amounts of Far Red.

This is all going somewhere – trust me.

Now plants are green, right? That doesn't mean they don't use green light. On the contrary! They photosynthesise it more efficiently. My (personal) theory is that is the reason why leaves are green: because they reflect the most efficient and abundant spectrum into the lower canopy, where fewer photons of green light can have the same photosynthetic value as more photons of red and blue light (that do not activate as many chloroplasts in the leaf).

So HPS can penetrate further by proxy – it produces more green light (and more far red light than typical LEDs) which is reflected deeper into the canopy. That is something that I think LED growers sometimes forget.

There are other reasons why HPS still performs well.

For the last 40 or so years cannabis has been selectively grown and bred under HPS. So any particular plant that performed well under HPS was bred from over successive generations. This means that cannabis has been selectively bred to perform well under HPS for decades. That will likely change as LEDs take over.

Another reason HPS can perform well is that is inefficient. WHAT?!? Yes, it produces more infrared heat than LED (converts more energy to heat than light compared to LED), but metabolic warmth is needed by all living things to speed up the organic processes (chemical reactions) of life. LED grows can suffer when there is not enough warmth – and cannabis especially needs warmth to thrive – so sometimes it is a good idea to throw a HPS or CMH lamp into a LED grow to increase ambient temperatures in the grow room/area. We even tell growers to do this if their rooms are too cold over winter.

All up, it is actually very hard to beat a HPS grow for overall yield where all the correct parameters are adhered to. That means having the optimum number of plants in the optimum area under the optimum amount of light with optimum nutrients and training. For any given area that has all these "optimum" levels, HPS can yield on par with LED.

HOWEVER! HPS will need around 50% more energy to do it, and the quality will never equal a UVA-enhanced LED fixture because there is not enough blue, violet and UVA light of higher energy to stress the plant into producing higher levels of secondary metabolitee (ie: cannabinoids).

So give HPS its due, but don't forget that it is 60-year-old technology that has been surpassed by LED technology that is only getting cheaper and more efficient by the day. HPS really has nowhere else to improve. Double-ended HPS may be better than single-ended fixtures, but that's about as good as it gets – or is likley to ever get – now that the world is switching to LED technology over HIDs.
I totally agree with what you’ve said, I never said anything to the contrary.

I wasn’t trying to say that lumens are important to plants as I also know this is not the case

I was simply stating that lumens from multiple sources can’t be added together.

and I fully understand that green and far red can transition through the leaf, in school we used a leaf filter on a cardboard tube that we looked at a light source through.

My secondary point was that seeing as the single source will have a hotspot in the Center then more light will pass THROUGH (not around) the leaf under this hot spot than it would if there were multiple sources delivering the same number of photons more evenly across the canopy
 

Billy the Mountain

Well-Known Member
I totally agree with what you’ve said, I never said anything to the contrary.

I wasn’t trying to say that lumens are important to plants as I also know this is not the case

I was simply stating that lumens from multiple sources can’t be added together.

and I fully understand that green and far red can transition through the leaf, in school we used a leaf filter on a cardboard tube that we looked at a light source through.

My secondary point was that seeing as the single source will have a hotspot in the Center then more light will pass THROUGH (not around) the leaf under this hot spot than it would if there were multiple sources delivering the same number of photons more evenly across the canopy
Respectfully, that's just not how it works
 

Blue brother

Well-Known Member
it's possible as that is what is happening in nature. you take 2 flashlights now into a dark basement and partially overlap their cones, there you can see it will be brighter where it overlaps.
that definition you cited is very base and doesn't forbid to calculate an integral over both as in treating both as single incidents and combining the result or do an approximation.
I mean regardless of whatever metric you use you may find it logically that its the light density that's being calculated, with a higher density equating more brightness and its irrelevant in that regard from which direction or how many sources the light was derived.

as for the fixture height it's about minimum distance, equal spread...the 1000w HPS in a closed hood doesn't benefit from a close proximity but a rail LED can. But the rail also can be mounted up high if the room setup allows it why not? as long as mostly the leaves get hit and not the light flies out of the next window...

from @Samwell Seed Well :

see they are both up high at the ceiling
it's about canopy PPFD
First of all thanks for the reply.

As you said, when we add more sources we are indeed increasing the light density where the light from both sources overlap. However we are not increasing the source intensity, which can only be done by changing the source.

Also I am not saying that people can’t position a rail light up high, people can do whatever they want, but the higher we position the light then the more air (obstacle) this light must pass through.
Which causes attenuation both by scattering and absorption but also reflection which in turn is reflected and absorbed by the lining of the space. We do not grow in a vacuum. And leds typically have multiple smaller cones that end up sending light down in a cube shape, whereas for the most part of it (not all of it) a single source hps with a decent reflector will send light down in a pyramid shape, meaning less air is in contact with the light on the way down to the canopy, which in turn means more light will hit the canopy.

Edit: tight config qb negate this to some effect and cobs do a bit better still
 
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Kassiopeija

Well-Known Member
double the source, double the light. or x300 it's additive if we think about number of total photons trapped inside a closed growroom

as long as we ignore UVC the loss from air is greatly irrelevant
 

PJ Diaz

Well-Known Member
my argument is that we can’t add up lumens from different sources because lumens by definition come from a single uniform source and that’s it.
You are arguing semantics at this point. You could also consider the "source" to be a fixture which is comprised of hundreds of diodes, similar to the way we view COBs and the electrodes on a HPS lamp to be a single source.
 

Blue brother

Well-Known Member
double the source, double the light. or x300 it's additive if we think about number of total photons trapped inside a closed growroom

as long as we ignore UVC the loss from air is greatly irrelevant
This doesn’t seem irrelevant to me, are you taking into account Rayleigh scattering. And also there is so much more reflection happening with a rail fixture hung high than say a cob or hid. Most peoples grow linings are less than the initial 98% claim which doesn’t take into account contaminants that are statically collected on said lining.
 
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Blue brother

Well-Known Member
You are arguing semantics at this point. You could also consider the "source" to be a fixture which is comprised of hundreds of diodes, similar to the way we view COBs and the electrodes on a HPS lamp to be a single source.
I’ve had no option but to argue the same point for so long which makes me look like a mad man or someone with an agenda. But that’s because I believe what I initially said to be the truth. The point I made certainly doesn’t warrant the amount of times I’ve had to defend myself about it. I stand by it, and I’ll say it again lumens can’t be added because they come from a single source only lux can be the cumulative value.

I’ve also said many times that cobs are closer to single source than qb panels and qb panels are closer than qb strip rail fixtures. But it’s not the electrodes In an hid lamp that are the source it is the arc which is a single source.

It certainly makes me look like an idiot to newcomers of the thread, who are just reading a couple pages with other peoples reply’s which insinuate I’ve bashed led vs hps when I’ve never at any point done that.
 
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xtsho

Well-Known Member
This is what I have in my flower tent. Does the job. No complaints. 4+ years of operation for $150. Probably 4 more years of operation left at least. I also have a 1000 watt magnetic ballast that's bulletproof like the old Subarus from the 80's.

A friend just gave me all their grow equipment so I now have another 600 watt digital ballast and sealed hood. I have a 4 ft 4 bulb HO T5 and a 100 watt Vivosun VS 1000. I'm running the VS1000 in the veg tent right now. The T5 is my favorite for starting seedlings and for the first few weeks.

 

Prawn Connery

Well-Known Member
This is what I have in my flower tent. Does the job. No complaints. 4+ years of operation for $150. Probably 4 more years of operation left at least. I also have a 1000 watt magnetic ballast that's bulletproof like the old Subarus from the 80's.

A friend just gave me all their grow equipment so I now have another 600 watt digital ballast and sealed hood. I have a 4 ft 4 bulb HO T5 and a 100 watt Vivosun VS 1000. I'm running the VS1000 in the veg tent right now. The T5 is my favorite for starting seedlings and for the first few weeks.

Haha! "Magnetic ballasts" and "reliable" in the same sentence. And just like a Subaru with a rusty exhaust, they get louder and louder . . . until they burn out! My mate's got a huge magnetic ballast graveyard. It includes some of my old ones.

Ooh! And remember the days when you had to stagger all your magnetic ballasts when they switched on to avoid a sudden current surge tripping your breakers? Fun times!

But seriously, yes they work. And they are loud and inefficient. But the most important thing is you are growing buds :cool:
 
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