LED Grow Light Forum

I'm an experienced HID grower thinking of moving to LED and have been reading all the junk on the internet. I'm so turned around right now but I want to wrap my head around this as I believe LEDs are most likely the future for indoor cultivation. Questions:

1) Are these claims that you can replace a 1000W HPS with a 400W LED system? This seems unlikely but this needs to be true if the 50% energy savings claims are true.

2) Whats the deal with lenses? I assume lenses eat some useable light but do they effectively make up for this by capturing the far field light? Has any meaningful work been done on these angles or is it just one manufactures claims against another?

3) 5w vrs. 3w vrs. 2w vrs 1w - which of these is most efficient in producing good growing light. It seems like early internet thinking was that bigger was better but then moved towards 3w as the best balance of power and efficiency. Is there a scientific consensus here?

4) Light spectrums - when I started lumens of foot candles was king. Now PAR comes into the picture. There is some debate in who produces the best spectrum (if that is even knowable) but is there consensus that you need certain wavelengths? Whats the deal with UV A and B?

5) I get that quality of component is important, that heat management is important and that the actual wattage draw that is important. Are there other things that aren't on my radar?

6) Are there good information sources that aren't biased that you could point me to. I would like to understand LEDs so I can make the best choice possible for my capital.

7) Are there good examples of grow rooms that employ a mixed strategy using both HID and LED lighting? Where I live it ranges in temperature from below freezing to into the 90s. Most of the year some heat from HID would benefit me and combining the lights I already own with some new LED units could soften the blow of the additional cost.

Thanks

Hi,
can't answer all your questions but I can give some opinions

i have 2 experiences with LED. a cheap-o 90 watt UFO and a CLW SS400. the CLW is pretty nice. does it replace a 1000 watt HID? no way. i would say it performs like a 600 HID watt in Veg mode and somewhere b/t a 400 and 600 watt HID in Bloom mode

the UFO was decent for vegging one plant in a dwc setup i had. got quality bud but very little quantity during flower. no penetration

i am thinking about my next grow being a combo of the SS400 and a HPS. use the LED for veg and maybe the first 2 weeks of bloom. then switch over to the HPS for the rest of bloom.

the SS performed very well in bloom but lacked penetration. the top 18 inches of my plants were awesome. really crystally buds. but belwo that is fluff bud. had i went with a scrog i probably would have had more quantity. but i don't really touch or cut my plants. just let them grow au naturel.

all the tech stuff i can't help ya. from the research i did, i think there are probably less than 10 good LED brands on the market now IMO

1) What RKY said except I'd put the SS400w about the same as a 400-600w hid in veg and between 250-400w (only because they don't make a 300w HID) in flower. Below 400w LED start catching up if the diodes are powerful enough, especially in veg. A SF200w might be better than a comparable tiny HID.

2) All LED diodes have lenses, some lights add extra lenses which will block a little light and LED lights can't spare any, imho. The tighter the lens angle the less the spread but the greater the intensity within that area. Wider lens angles sacrifice some penetration in order to cover a larger area. CLW uses very powerful 5w diodes with 120 deg angles to try to balance both penetration and coverage.

3) 1w diodes generally are more efficient than 3w (then 5w) if you're comparing LED watts to actual draw but they lack the penetration to handle anything meaningful, depending on the crop of course. I can't speak for scientific consensus but based on over 2 years here I'd say that even 5w diodes aren't powerful enough to replace bigger HID lights in flower. I don't see much reason to use LED grow lights that are under 5w for anything more than clone/mother/seedling/early veg. I'm looking forward to the next gen LED which I assume will be between 7w and 14w.

4) Spectrum is important but many manufactures miss the mark. You can find LED grow lights from 1 to 14+ spectra and they all claim to have the best ratios. I've made my case against par as a meaningful measurement for comparing cannabis grow lights to each other but I don't have anything better to replace it with either. Lumens isn't "everything" either. The best way to compare one light to another is to grow with it. Comparison grows, where the only thing different is the light, would be a better indicator if the grower was at least semi-experienced with one light. UV A-B can harm plants and animals in large doses but UVB has been shown to increase trichome production which is a good thing too.

5) Yeah, price, spectra, heat management, diode intensity (more w = better), lens angles, craftsmanship, warranty and efficiency are the biggies. Ask some of the members here about the obvious quality differences in some cheaper knock-off lights and a quality LED light.

6) What is your level of understanding of light and grow science now? There are a ton of articles just about the science of LED and light in general. As far as unbiased opinion regarding LED vs HID, based on real life grows, forums are your best bet. There is often good science information even on manufacturers websites but those are also often full of sales/marketing propaganda designed to sell more product and so lines get blurry at best and crossed at worst.

7) We had some mixed HID/LED journals but I'm not sure what happened, I think the OP ended up changing things up mid grow but RKY's plan to veg with his SS400 and flower with a larger HID is probably wise with his growing style. You could use LED to supplement a smaller HID or just use the HID and reuse the heat. Larger LEDs still make quite a bit of heat so heat management in the grow area is still important. Although with colder climates you might even need to add heat in the winter with LED lights.

What is your goal?

First of all, i don't grow Marijuana so i can't comment on that directly but i grow a lot of other plants using LED.

Yes LED's can be far more efficient however there also needs to be a lot more planning involved to get the best out of the systems. Now i build my own systems using individual 3w led's, which is probably the best way to do it as you can customize things but you have to be careful of the voltages. I think this is the main problem you will see in the cheap chinese systems you get where the actual draw is lower than the rating given. They try to build systems that adapt to all the international voltages and cut costs by pairing up different led's making the output much lower. If you ever look at the individual led's you'll see that the red ones are rated for 2-2.4v each but blue ones are 3-3.4v so you don't want to pair those in the same voltage string as the blue ones will bring down the current on the reds reducing output. They will also work on the lowest voltage rating to cut costs on the wiring which will also reduce output.

Having the right spectra at the right time is also important, with a lot more blue during the growing time than when blooming. You will also notice that there are two spectra of red and two of blue, which is due to the two types of chlorophyll. If you are growing only one type of plant checking the ratio of chlorophyll will help in getting the right ratio between the spectra's. It's also a good idea to have some white led's in the mix, only a few and an even mix between pure white and warm white. I'd say between 2-5 percent white. The biggest mistake is having too few blue's during the growing period of the plant as this will hurt the overall yeild you will get as while it's commonly referred to the 'vegging' time, what the blue led's actually do is stimulate root growth. Without a good root system, your plant will find it difficult to provide a good yield in the blooming period.

Beam angle is also an important factor for many reasons. With normal bulbs the light is produced in all directions evenly and require a reflector to bounce the light towards the plants, but with led's the light is directed. This will cause several problems, the first being the plants directly underneath will get more light than those at the edges so having multiple smaller systems spread out and overlapping is better than just one big system (or if you make your own, spreading the individual diodes out evenly rather than clustering). As you don't need a reflector you won't also get any scattering of part of the light so all the top leaves will shade out the lower ones giving what some people call lack of penetration. It won't matter how powerful the led's are, without doing something to prevent that the light won't ever get to those lower leaves but the solution is simple and has a secondary benefit. All you need is one of those rotating fans (the ones than move left and right when turned on), put it on the lowest setting and it will cause the plants to 'sway in the breeze', moving the top leaves about so they don't block out the light to the lower leaves. The secondary benefit is that the swaying makes your plants strengthen it's stem making the plant healther in the long term.

very good post Puggy on LEDs.

but i strongly disagree on your point about penetration. i think the wattage of the LED does matter as far as how much it will penetrate. i have 2 LED's: a 90 watt with 1W leds and a 400 watt with 5W leds and there is a HUGE difference in the penetration of each unit.

and the simple fix of a fan just won't cut it.

don't get me wrong, i really like my SS400 but it does have it's limits as far as plant height and how much it can penetrate.

can you post a pic of one of the LED you built? i'm curious to see what they look like. what total watt LED's do you build?

RKY

rkymtnman wrote:but i strongly disagree on your point about penetration. i think the wattage of the LED does matter as far as how much it will penetrate. i have 2 LED's: a 90 watt with 1W leds and a 400 watt with 5W leds and there is a HUGE difference in the penetration of each unit.

and the simple fix of a fan just won't cut it.

don't get me wrong, i really like my SS400 but it does have it's limits as far as plant height and how much it can penetrate.

can you post a pic of one of the LED you built? i'm curious to see what they look like. what total watt LED's do you build?

RKY

That's right. I agree with some of his data but not all of it. Not just the penetration issues either. Spectra comments are a little off but close. "Beam angle" comments are a bit off but close. I don't feel like picking it apart though.