SisterMaryElephant wrote:
Mother Nature is often a limiting factor. You *can* beat the Sun, except when it comes to price. Plasma lights have potential but I'm not switching to plasma yet.
There is a theory, that we've talked about on the forums, that suggests that the IR spectrum may be why LED lights lack the yield that HID lights can produce. Some have suggested that raising the ambient temps may help LED lights yield better since most of the LED lights lack the IR spectrum.
The point still stands; you can't expect top-shelf results by skimping on light and not enough w/sqft is skimping. Suggesting that small light (300w) will properly cover a large space (4x4) is skimping (18.75w/sqft) and not based on real world grow results. CLW suggests 40w/sqft for flowering with their 5w diode LED lights and I'd suggest that even that is exaggerating a bit if you want top-shelf results. You'll certainly do better with 40 than 20 or 30 but even with higher numbers HPS is still king...for now. I've yet to see any LED grow that beats top HID grows.
I'd love to be proven wrong though...
SisterMaryElephant wrote:(Welcome to the forums!)
I believe that leaded glass will block UV and IR but most bulbs and hood glass should be lead-free. I think the plasma inside the bulb creating IR is why it heats up.
Good question. The amount/intensity of light certainly affects growth but how that light is measured can skew the numbers one way or another. This is why I dismiss PAR as a meaningful measurement. I'm not sure about that 95% number either but that's not important right now.
There are clearly multiple factors for grow lights; spectra, intensity, coverage, heat management, cost, etc. Many growers use grams per watt to compare efficiencies. We've found that more watts per square foots usually results in more yield and better density. UVB seems to stimulate trichome growth. Really there are pros and cons with virtually every growing decision we make and you have to take into consideration other factors like environment, genetics, experience and grow styles when deciding on lighting choices.
SisterMaryElephant wrote:You don't have to agree but the makers of the EYE Hortilux HID lamps have charts showing output above 700nm, even over 740nm on the MH and HPS bulbs so the lead-free glass isn't blocking it as much as you thought. Also UV is 100-400nm, it's just the UVB that's close to 300 and HID specras range under 400 too.
SisterMaryElephant wrote:HID certainly outputs less IR and UVB than it does white/red/blue but that doesn't mean it's not used by our plants and...maybe...that could be *partly* why LED grow lights aren't keeping up with even equal powered large HID grow lights. Higher powered diodes that will surely show up eventually might allow LED to take the crown as king of the grow lights but that's not today.
SisterMaryElephant wrote:Since this is a grow light forum and we're talking about comparing grow lights, I still say PAR is more marketing hype than useful measurement. The one with the higher PAR isn't always the better grow light and that's a problem since that's how many manufacturers make the claims/implications that their lowered powered LED lights will outgrow higher powered HID lights. Results don't back up the claims, at least not with cannabis growers.
SisterMaryElephant wrote: The inverse square law can't be ignored but there's still no way that that less than 300w of fluorescents will outgrow 600w of HID unless you're doing something wrong on the HID side. You can't cut half of the power and expect equal results, that's where the LED claims are failing too. You can't compare flower quality/density, imho, either. HID is superior in terms of intensity and that's a big enough difference. Can people grow with fluorescents? Of course, they can grow with incandescents too...if they wanted, but there are better lights available. Sorry but fluorescents are near the bottom of the barrel for me. I wouldn't use them for more than rooting clones or starting seeds but people are free to use what they want.
SisterMaryElephant wrote: LED lights can have varied diode beam angles, they're not always pinpoint focused. LED and HID light *can* be kept closer than 1 foot but as we know, the closer to the canopy, the less area it will cover too. Higher powered, more intense, lighting can also bleach the tops of plants. LED manufacturers "stretch" the coverage by suggesting higher placements than could be achieved. Also partly based on the assumption that they can use less watts/sqft because of the tuned spectra.
SisterMaryElephant wrote:I'll skip around a bit, I just don't feel up to my typical verbosity levels.
I see the source of the confusion now. You're being more specific than I was. When I wrote about HID lights producing UV and IR I mean light within that spectral range which are both clearly produced by HID lamps. I have no idea how much IR/UV is produced or blocked when you get on the far ends of those scales (far IR and EUV) but I did read this:
"Ordinary glass is partially transparent to UVA but is opaque to shorter wavelengths, whereas silica or quartz glass, depending on quality, can be transparent even to vacuum UV wavelengths. Ordinary window glass passes about 90% of the light above 350 nm, but blocks over 90% of the light below 300 nm."
Since we're not talking about ordinary window glass here I'm guessing HID lamps and better hood glass use the silica/quartz kind, and that should settle that.
SisterMaryElephant wrote:The reason is that not all lights are the same. Fluorescents HAVE to be close because they lack penetration which might be fine over clones or seedlings but not as good for taller plants. Because fluoro has to be so close, it doesn't cover as much area either. LED is somewhere in the middle with better intensity/coverage than fluorescents but not as much as HID lighting.
My first grow was back in the 70's but I've never done side by sides with fluorescents and HID. Nor will I. I also won't do a side by side with incandescent bulbs even though I know you can grow cannabis with them if you have enough bulbs and deal with the heat.
I don't tell people what they can or can't grow with, you can use fluorescents if you want. I keep saying it; there's no one right way to grow but if you get...say...1g/w under the fluorescents (fluffier popcorn buds too) and you got .5g/w under the HID then you did something wrong under the HID because I know what they're capable of. Don't take it personally, it's not meant personally, I'm just trying to help people here.
SisterMaryElephant wrote: I understand the dilemma (that goes back to the inverse law too) with beam angles, that's why CLW used 120 on the 5w diodes they run. If they ran 90, they'd have slightly better intensity but they'd lose coverage. The obvious thing I would try is 90 degree lenses on 10w diodes and just add more of them in a larger fixture to take care of the coverage. As far as I'm concerned, the myth (sales propaganda) that smaller LED lights can grow as much cannabis as larger HID lights has been busted by journal after journal. Even my local hydro stores say that with 5w diodes a 400w (actual draw) LED is about the same (yield wise) as a 400w HID. The idea that you can outgrow a 1000w hid with 20-70% less power is just not backed up by anything I've seen so far. That's why us older growers switched from fluoro to HID in the first place.
Even though I know that HID is a superior light to LED (and both better than fluoros for flowering cannabis), I still volunteer my time here in an LED forum helping people get the most they can with what they have.
Hope that helps...
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