Led light advice needed

the bro

Hello all.
I want to start using a led light, just not sure if they are penatrative enough. How tall can you grow your plants, do they flower all the way up or just at the top. Can't find any info anywhere, all I keep finding is how far the light should be from the canopy. No info on advisable plant height at switch/ flowering/ harvest. Thanks in advance!
Cool and deadly;)


New member
I think it depends on the light you buy, Spectrum King seem to penetrate quite well, they are on youtube!


Well-known member
I've had success with my home-made 600 W COB setup in my 4x4 tent. I estimate it's roughly equivalent to a 1000 W HPS. I got 1.4 lb from my first grow. Glad I didn't get a "blurple" light, if for no other reason I don't need to wear special glasses and pictures of buds are in true color.

As for penetration, I've been told that COB LEDs don't do as well as MH or HPS, but for a given flux of photons I don't understand how one light source will penetrate a canopy better than another. People talk about penetration but I haven't seen any technical articles on the matter or a side-by-side grow comparison. I think it's a matter of not overcrowding your tent like I do and defoliating the bigger leaves and lower growth. Here's a picture of some Strawberry Cough I have flowering right now, and I guess you could blame the yellowish lower leaves on poor penetration, but I blame it on an crowded tent (7 plants in a 4x4) and on a need for more defoliation.



MNS Hall of Fame
Greetings bro!

When i switched from HPS to Cob Led i couldn't see any difference on light penetration and also not seeing why one would be better than the other when the light output stays the same. I have grown plants close to 1,7meter with my setup its like what marcus said as long as it isn`t to crowdy they give fine penetration. Just go like you would with hps.

I also would stay away from the blurple led lights. DIY is the cheapest way but nowadays theres also a few guys online where you can buy those build units with cob leds on them for a fair price.

like these guys
Todogrowled shop, best grow led - The bests LEDs - Todogrowled

good Day!


New member
I like the Secret Jardin LEDs they released, they got the 3ft version now as well. The blooming version has IR as well so it is the complete photosynthesis delivery, still figuring out how many would suffice to properly illuminate a 3x3 or 4x4 area. I have a hunch that it might be cheaper than the pro-emit or Todo thingies with the 3070s and 3590s which are still quite a lot to invest for a hobby...
I am using the 60cm blooming version atm and i loved the results so far.


just do the math, lets assume you need 2 bulbs per year, thats about 70 euros for cheaper bulbs to 120 euros for brand names like phillips ...

in 5 years, thats 350 or 600 euros, for the bulbs only ... now we need the driver too, digital, starting at about 120 euros, there you have it 470 to 720 euros for HPS calculated on a 5 years timeline

as some of you might now, im working in our industry / business , in a growshop/hydrostore, and its a common daily routine , the talks about led and so on, ppl get curious and want to know everything, unfortunately many customers of mine arent the brightest bulbs out there and i have to do physics - biology - chemistry 101 "lessons" to explain "simple" things with laymans words, as marketing and advertising are "cutting" through all logics, situations like "i have 1000 watts of led in a 2ftX2ft tent" .. WTF .. ???

there is a trend, many are hooked on the austrian company "SAN LIGHT" , they have 3 different LED modules, which are really rocking hard !

some ppl make a change 1:1 , meaning the have the same power bill as before with HPS, instead of 600W HPS they use 600W LED - those are the ones that are "squirting" all over the place bc - finally - they broke through the magical 1 g/W barrier, and numbers like 1,4 g/W to 2g/W become normal for them, they are all happy and its all good

then there are the ones who like to lower their bills while keeping their yields, they "downgrade" from 600W to 400W of LED and still get their 600 grams at least

most important things to keep in mind :
what chips are being used
how efficient are they being driven
how many real watts are drawn out of the wall
what spectrum is being used

there is guy on youtube, he is having hundreds of tutorial videos and how to videos on building your own LED lights:

hmm lost my train of thoughts ... there are still some things on my mind i cant remember right now, but when i do, ill post em


New member
mau5 rulz

totally agree growmau5 knows his stuff, however i do small time growing and i dont intend to invest a fortune in equipment while the legal status in germany is as it is right now. So i was hoping that a smaller fortune spent might still yield in the end, if only extra terpy quality as im growing it for my medicinal use, well mostly. Since we got your attention, is there an supplemental UV Light you would recommend deran? (for twice a day 30m)
LED only used to have some issues in maturity.
maybe from lack of UV.
They seemed to take up to cpl weeks longer to ripen, and fox tailed a bit.
Are these issues sorted now, in the new gen leds?


regarding legal status in germany ... its worse than before "legalization", only 2 patients have the official permit to grow (and their permit is running out, as its only legal for the duration of a year, then you have to renew it, which will not be prolonged), all others have to get their meds from the pharmacy where a gram cost from 25 to 40 euros (not kidding) - the problems are coming from the health insurances, highest priority is to ban all growing plants .. to move all patients to the pharmacy ... which isnt the worst idea - but .. but ... who is gonna pay 40 euros a gram of "bedrocan" a F2 jack herrer, that got "cleaned" with the help of gamma rays .. yummy ... anyways, the idea is that those health insurance companies take over the payment for the meds, as it is with any other meds too ... for example you have real cold, the doc prescribes antibiotics, lets say penicillin, and the bill is paid by your health insurance company ... so far so good .. when it comes to weed, they stop paying and you have to go through different levels of courts and judges and bureaucratic shit , even then its no guarantee that those costs will be lowered .. and there is absolutely no logic behind their decisions other than keeping that plant unreachable - bc they know - they have a treasure which is actually working and healing ppl ... poor doctor will become poor, as his patients get healthy ... he cant make money with them when they are healthy ...
i know of a strict situation where the health insurance company has no problem paying opiates for him (which are double the cost of weed) but wont pay weed, its a big mess in this country as nobody is really prepared for change and weed and its users are still stigmatized like 20 years ago, its a local thing for change, and im happy living in berlin, as berlin is the most relaxed city in germany when it comes to inhaling
(even the grow gurus from legal states were more than surprised how relaxed berlin is, they felt its more legal than in colorado and/or california .. said both . mr tommy chong and mr ed rosenthal, who were here in february/march at the icbc; i was smoking infront of my hostel when i moved here 2 years ago, when i finished i turned around just to become terrified, as 2 cops were standing 3 meters behind me and were watching the entrance of the hostel, impossible that they havent smelled it, impossible that they havent seen it ... im not used to such situations as i grew up, like all you other freaks ;) , in a time and a place where this plant was illegal and all "actions" around it where handled differently ... now imagine how this ascent is being "transported" across the whole country ... yes, it takes time, a lot of time, there a so big gaps that you can easily think you are in another country , from totally legal in berlin (tho not really legal on papers and in reality) to being handcuffed and jailed and having your apartment searched because of a zip lock baggy !!!without!!! content, which happens in munich (in the south); you can say the further up north, the more is the plant relaxed and "legalized"

as supplements PatientZero ,
take a look at sanlights M30 module :
- about 130 euros , 30 watts (only - therefore supplemental) - but bc of its tiny dimensions, its no problem to integrate them into any small room/place,
or, like somebody further up mentioned the led from secret jardin , they cost about 70 euros and they are a good option for interplant lightning , and while we are here, phillips has a new range of flouroscent tubes, like the oldschool lights, in length of 60cm, 120cm, and 150cm - instead of gas, they are filled with LEDs, also bc of their design they are optimal as sidelights
and my favorite module from Hans (the guy behind the bonsai hero scissors) , favorite bc its has the best price value , a cheap build - a mini series - but with the best chips out there - unfortunately its a blurple panel :
as you see, you have a few options, veg/mother or bloom or veg/bloom and a noise free version without fans from 60 watts to 180 watts (only the small 60/70W versions are passive cooled, the stronger ones need active cooling, which is also heat controlled, meaning the fan is only blowing when it reaches a predefined temperature, otherwise its noise free) , 2 of the 180W panels are supposed to replace a 600W bulb, i cant say more bc i have no direct experience, i can only tell you what my customers tell me, and there is clearly a trend visible :
about 2/3rds of all buyers are satisfied , their results are equal or better than before the switch , but 1/3rd dont get along with them, they fail, i cant say really why, i mean a little higher temps (2-4 degrees) and a touch more Ca is the only change you have to keep in mind, and if you neglect it, it shouldnt be such a big problem to "give up" a whole run- but it happens - so im advising every single customer not to switch all lights to led, take only 1 bulb and see if its working for you, bc if its not (can happen) you only "loose" 1 bulb and not the entire room

but now for something completely different !

i read the word terpens - and unfortunately no high pressure sodium light, or metal halogen or even led cant compare to the results of cdm/cmh bulbs, they give off extra uv radiation thats pumping up thc and terpen levels

i came across john berfelos youtube channel, he "showed" up somewhere in the shadows of mark - bubbleman - well this guy has not only a growroom, no sirs, he has also a lab toy , a gas - chromatograph ... so he is growing the same cut below hps, led and cmh; he is testing with his toy his results, and while hps and led are on par regarding quality and quantity - cmh is overtaking both
im not sure that this is the video im thinking of, if not its another clip from him , all in all a great channel, actually i was following his 99% resin head hash ...

Northcliffe rose
the issues you were speaking of are the blurple lights, that have only red and blue colors, those can be problematic with some strains, dont forget - most of them (strains) were "acclimatized" to hps lights the last 40/50 or so years, so they thrive best below this kind of lights ... actually its the landraces from the equator that make problems, or hazes in general, that love blue lights more than orange/red lights , and some typical outdoor varieties have also some issues with those blurble lights

we are here talking about COBs (chip on board) , they are all white (in general) having full par spectrum , in different "colors" /
"shades of white" from 2700K to 6500K , but all white in general, with them there is no issue anymore with problematic varieties , they will feel like home :D

man man man - im such an idiot - we all know this already by now (i hope) :D

i was reading LED supplements - but you were typing UV supplements ...

anyways - some good news - cmh/cdm bulbs come in different watt versions, from tiny 5 watt or 10 watt bulbs, to 35, 70 and so on watt versions , all up to nearly 1000 watts

combining both worlds LED + CMH/CDM is the best thing one can do besides simulating the sun (which is impossible), meaning quality and quantity cant be better , no other light sources can give you these results :)
and the best for the end, ive seen a dozen or so threads where the grower got as much yield with 315 watts of cmh (1 bulb) as with 600 watts of high pressure sodium lights;
and meanwhile they are also made double ended, like their cousins hps and mh

i hope i havent made too much complications for you by extending ideas and solutions :D
Hi Deran.
I am lucky enough to have a cpl of cdm@315w.
If I use them at low light ratio, <400w metre, they start to show good gram/watt.
They aren't really magic.
Although the quality and perfume are great.
They also tend to ripen the flower a bit quicker, than pure HPS light.
The DE green master I picked up cpl weeks ago is smashing it to pieces, in efficiency.
A 1000w or DE cdm changes things.
Is it true DE tech, or just two globes running back to back?

Also, you speak about the 40-50 years of acclimatisation to high discharge lighting.
I think it is more selection.
If you veg and bloom under pure cdm spectrum, the plants behave differently.
they have smaller leaves, n different branch structure, and the earlier maturity effects the outcome as well.
I would just think to fix your spectrum, then select to that spectrum.
the plants most suited will stand up.

When they foxtail and refuse to mature, I think that helped some of the LED yields.
if my ssh takes two weeks longer under led you may get 1.5grm\watt plus.
but 11 weeks compared to 9 means you use an extra 20% energy.
an hps yielding 1.2 gramme\watt, in 9 weeks is exactly the same efficiency.
Led at 250 watt per metre may yield 375 gramme bloom ( 1.5grm\watt)
600 watt of led, per metre, might not produce 900 gramme of weed.

Cree cob @2700 has incredible spectrum.
My next purchase, I hope.
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New member
@deran thanks for explaining that in detail. It's appreciated, so whats the german term for cdm bulbs to look for? Is there a supplier in germany you would recommend?
Now for a 1m² how does a combination of 2 of the 42W hanging left and right of the CMH sound? Thats like 500€ +/- 50 bucks banging out 400W of terpene rich fastripening ladies. Me thinks i could be good with that...
Deran, the 315w emits as much ppf as a 600w MH, running on a magnetic ballast.
How do you equate them to a 600w hps?
They are closer to a good 400w hps.

Philips make the bulbs, or solistek can match a ballast to their own globes. The solistek combo is very good.
I use hi-par ballast.
They use a square wave, low frequency ballast.
Be very aware the ballast has been designed specifically to run the globe.
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hey guys

well i personally dont have first hand experience with those 315 bulbs, and also not that much from my customers, i wrote only that what i came across the webz while surfing, and one of those statements was that somebody got as much yield as with a 600 hps, not more or less, i mean i dont know how good this grower is, was it his 2nd or 3rd run etc etc ... not very objective those bits of infos, but at least a kind of pointer - towards where this voyage is going to ...

cmh/cdm has become real double ended technology, as far as i was able to find out with given links, come in and help me, bc im still not 100% sure about it, bc of the language barrier


and so on and so on .. BUT BEWARE :
there are some differences regarding lumen output, color temps, photon flux and so on, as far as i remember, the 315W bulb (the so called agro spectrum from philips) was the only real alternative - compared to their bigger "brothers like 630W and 945W" which were missing some very important things ....
but i also might think, that those issues got solved in the meantime, and that those bigger versions are now true bigger versions (a multiple of the 315W in all aspects) ...
anyways - further infos needed for clarification - for you - for me - for the reader out there - just to get this settled

Also, you speak about the 40-50 years of acclimatisation to high discharge lighting.
I think it is more selection.
If you veg and bloom under pure cdm spectrum, the plants behave differently.
they have smaller leaves, n different branch structure, and the earlier maturity effects the outcome as well.
I would just think to fix your spectrum, then select to that spectrum.
the plants most suited will stand up.
i need to clarify this further: i was speaking of the blue - red (blurple) led panels which can be problematic with given special plants. the idea behind is: "skunk and its gens" (on purpose this variety for this example) has been below hps bulbs since the 60s, for the last half century. if it gets put below those blue-red panels, this could trigger and result in problematic growth ... in this example the greens are missing entirly, there is tiny fraction of green within hps, but lets say that this loss is the reason behind it ...
with the new COB chips (who have a full spectrum-no color is missing inside the par spectrum) this cant happen as they have green colors in their spectrum (for this example and in relation to it - just dont plz miss interpret my words differently for another different situation)

be back later - cant concentrate anymore further this night, sorry, but wont forget to come back and to give more answers later on
Thank you Deran for your reply.
Unfortunately the DE CDM is not supported by any electronics manufacturer.
They have no ballast designed for them.
The globes are produced by companies who simply want to profit without concern to their client.
They are running on high frequency pulse ballasts, that are not designed for them.
They are cheap bulbs, that are being sold in cheap units.
The brand is "master color"
Unlisted Chinese producer.
630 watt globe a third the price of Philips 315 watt globe.
Too good to be true.

CDM is not magic. Anyone expecting them to do what a 600w hps can, by simply swapping the lights, will be very disaponted.
HPS can do about 2+umol/j.
LEC mh is about 1.9.
But the HPS is emitting a spectrum that promotes bulk over 'quality.
It takes two 315 watt CMH to equal a good 600 watt hps.
That is fact.
Hype sells lights.
Hype also creates dissatisfied customers.
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OK Led and CMH may have high PAR spectrum%.
So what?
HPS is about 30%.
MH about 60%.
CMH 90%+.
You can't say that standard MH is double as productive as HPS.

Terms such as '% of PAR' are like lumen or Calvin ratings.
Lumen and Calvin° are terms that should mean little to people using horticultural lighting.
Frequency spectrum is more important than % of PAR.
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Active member
Try watching some videos by grauman5 on youtube and there’s some other engineers that share information with him and they compete.
Samsung is making some leds now that put out over 200 Lumens per watt and are made for holticulture.
So instead of cobs now it’s easy to get a pcb board with 500-1000 leds on it and there’s UV,IR,photo red,far red leds that supposed to actually work.
Efficacy has almost reached 3.0.
So more par light less wattage.
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