600w hps or mh
- Thread starter Bazza555
- Start date
Herb & Suds
Well-Known Member
Some folks put in a MH the last two weeks
and I know a couple commercial growers who only use MH bulbs
The thought is it increases bag appeal
kmog33
Well-Known Member
twalte
Well-Known Member
I run MH thru veg and the first two weeks of 12/12 to minimize stretch. Then I go to HPS. HPS is a much more efficient light as I understand it....more light generated per watt. Some say the last two weeks help because the metal halide bulbs put off UV light. However, the glass in my air cooled hood blocks UV light so I see no point. (I run separate UVB lamps too for terps)
Grow Lights Australia
Well-Known Member
Neither. LEDs are more efficient and put out less heat for the same results. And we've proven you can get the same THC/CBD/Terpene results with near-UV as you can with added UVA/UVB.
There's also the issue of layout: you have a square-shaped area and having two or three HIDs in a row is going to light up a line down the middle but leave the edges darker. HIDs under hoods have a fairly square light footprint, so in a square area, you really need one in each corner or similar.
If you're going to go with another HID, I'd go with a CMH over an MH. Better spectrum and efficiency (equal to HPS), and added UVA etc.
Or you could hang up some fluorescent reptile bulbs for added UV. Not as efficient, but you could space the fluoros out for better light spread.
Cheers for info guys appreciate it, think ill stick to what ive got and try MH bulb next round possibly, only my first grow so will try dial in with what im using atm seeing as i invested a fair bit into the setup, will definitley look at LEDs but will do alot of research and asking on here too. Thanks heaps guys, once i can pull a pound from what ive got consistently ill definitely look at the switch.
mr. childs
Well-Known Member
which uvb lamps are you running ?
mr. childs
Well-Known Member
the hippies always mentioned something about mh for the headstash & hps for the cash
kmog33
Well-Known Member
Can you link me to results of identical tests with and without uv using the same amount of light in led over de hps? I’m curious as to who’s doing this testing large scale...because I’ve honestly never heard that you could Take light quality/spectrum away And get the same results. Seems the exact opposite argument than leds do better because of better spectrum and higher efficiency.
Grow Lights Australia
Well-Known Member
This is one of the tests I was referring to: https://www.rollitup.org/t/thc-cbd-terpene-test-results-uva-vs-uvb-vs-none.1001617/
Here is another: https://www.karger.com/Article/Fulltext/489030
It all depends on how you define "light quality/spectrum", as not all wavelengths are absorbed equally by plants, and different wavelengths elicit different morphological responses. Typical blue-pump/white phosphor LEDs do not necessarily have a "better" spectrum than, say CMH, because a lot of LEDs lack that critical 400-430nm area of the curve and are also deficient in cyan, deep red and far red. The main advantage LED has over HPS, MH and CMH is in terms of efficiency. There are also spectral differences. But again, not all LEDs are the same, so it depends which ones you are comparing.
It's certainly not a "zero sum" game where all spectra are equal and taking away or adding any wavelength on the curve has an equal and measurable response. For example, green light is photosynthesised more efficiently than other colours, but much of it is reflected – hence its lower rating on the McCree Response Curve. HPS emits a lot of green, as does MH, and even CMH for that matter.
Other wavelengths correspond to various Chlorophyl (A and B) absorption peaks, as well as Phytochrome Red and Far Red, and Betacartone and other terpenes. Cryptochrome is interesting, because it regulates photomorphogenesis in plants and happens to peak around the 405nm mark – which most LEDs do not have in their spectrum.
This makes very good reading if you have time, as it explains the various plant responses to different spectra: https://courses.lumenlearning.com/boundless-biology/chapter/plant-sensory-systems-and-responses/
kmog33
Well-Known Member
Awesome. Thank you.
kmog33
Well-Known Member
Those reptile uvflouros are fucking garbage for efficiency, are fairly expensive watt/$, and need to be replaced constantly though. I think cmh sort of pulls ahead here as far as not needing to supplement uv and bulb lifespan. A pot of interesting info. Thanks again.
Grow Lights Australia
Well-Known Member
Fluorescent bulbs are actually not too bad. Apart from the cheaper set-up cost and easy bulb replacement, fluorescent lights (like other mercury-based lamps) generate a plasma that emits UV light that is then converted via a phosphor into visible light. Just like LED, there is a conversion factor when UV light is converted to longer wavelengths. The higher the conversion rate (that is, the bigger the difference between the original short-wave radiation, or UV, and the longer-wave visible spectrum), the less efficient the light source is.
What this means is that if you start with a UVC source (fluorescent) and convert it to UVB, less energy is lost than if you convert it to UVA or visible light. So fluorescent reptile bulbs are actually quite an efficient source of UVB light, and to a lesser extent UVA light, even though they are not a very efficient source of visible light.
There is also the problem of lifespan. UVB is high-energy and very destructive. UVB LEDs need ceramic packages (housings) to survive, compared to plastic packages for blue-based LEDs. This makes them more expensive. Ultimately, it is the reflector material and encapsulating lens in the LED that degrades over time with exposure to UV light which shortens their lifespan.
This is all a long way of saying that currently there are few cheaper and better sources of UVB than fluorescent bulbs – which is why they are still so extensively used for UV curing and bio-control. Mercury vapour lamps are actually a better source of UV than CMH. CMH puts out a noticeable amount of UVA and near-UV – which has been proven to increase cannabinoids and terpenes – but they put out only a very small amount of UVB.
What this means is that if you start with a UVC source (fluorescent) and convert it to UVB, less energy is lost than if you convert it to UVA or visible light. So fluorescent reptile bulbs are actually quite an efficient source of UVB light, and to a lesser extent UVA light, even though they are not a very efficient source of visible light.
There is also the problem of lifespan. UVB is high-energy and very destructive. UVB LEDs need ceramic packages (housings) to survive, compared to plastic packages for blue-based LEDs. This makes them more expensive. Ultimately, it is the reflector material and encapsulating lens in the LED that degrades over time with exposure to UV light which shortens their lifespan.
This is all a long way of saying that currently there are few cheaper and better sources of UVB than fluorescent bulbs – which is why they are still so extensively used for UV curing and bio-control. Mercury vapour lamps are actually a better source of UV than CMH. CMH puts out a noticeable amount of UVA and near-UV – which has been proven to increase cannabinoids and terpenes – but they put out only a very small amount of UVB.
twalte
Well-Known Member
I’m running the California Lightworks solarstorm UVB lamps.
mr. childs
Well-Known Member
the 880 ? are those 2ft t-5 bulbs ? do you know of the manufacturer of the bulbs ?
twalte
Well-Known Member
This model...yes, they are 2 ft (22inches really). I believe the bulb is proprietary to CLW.
SolarSystem® UVB
The latest generation high output UVB T5 fluorescent bulb. This system is perfect for a single light in a tent or several hundred lights in a large commercial operation.
californialightworks.com
mr. childs
Well-Known Member
the crazy part is that that system is $100. the agromax is half of the cost. https://www.htgsupply.com/products/agromax-pure-uv-t5-bulb-2-foot/This model...yes, they are 2 ft (22inches really). I believe the bulb is proprietary to CLW.
SolarSystem® UVB
The latest generation high output UVB T5 fluorescent bulb. This system is perfect for a single light in a tent or several hundred lights in a large commercial operation.
GrowBright 2 Foot T5 Grow Light - Single | HTG Supply
The GrowBright Single-Lamp 2 Foot T5 Fixture is perfect for a wide variety of indoor garden lighting uses. Get it now with fast & discreet shipping guaranteed at HTG Supply!
www.htgsupply.com