MH vs HPS in bloom

[whazzup]

I apologize for my bad English, higher frequency is shorter wavelength

About the colors and efficiency: It's not all quantum efficiency you are looking for, it's also many other processes that are driven by the different wavelengths. Green light actually is more efficient in high intensity white light than blue and red. There are also many more pigments than just chlorophyll.

The PAR curve (well, it's not the PAR curve but the McCree curve) was defined in the 70's of last century and defined for light levels of about 100 umol. Since then a lot more research has been done and at high intensity the efficiency of the different colors is much closer than the original McCree curve.

So, translating the McCree curve in a graphic in "plant requirements" is a bit let's say inaccurate.

 

[daylighting]

Some great food for thought there. I guess the PAR (or McCree) curve also shows what the chlorophylls/beta carotene/other accessory pigments absorb; not all the light absorbed does good things and can even have an inhibitory affect on tissue synthesis and bud formation!

I've been taking the PAR curve as pretty much verbatim since it's bounded around everywhere, but I'm just beginning to chip away at the whole photosynthetic issue thing. Lots of reading to do for sure!

 

[Stonefree69]

I just saw a show about Alaska and how many world record vegetables are grown there. Besides genetics and grow methods (usually outdoors in soil) they credit the long hours of Alaskan summers (about 20 hours/day). In the "land of the midnight sun" peak radiation is only about 1/2 what it is in lower latitudes. So given a choice of more light if you already use the 50 watts/sq ft rule maybe longer veg hours could benefit.

Marijuana being a C3 type plant besides being able to use more CO2 can also benefit from longer light periods in veg. Currently I use 18 hours in veg using MH (also a mix of 3,000k & mostly 6,500k T5s in early veg). Now I wonder how much better 20-24 hours would be. Plants will have less of a shock going from 18/6 to 12/12 than over 24/0. You might save a week of veg time but have to adjust for at least few days going to 12/12 from 24/0.

 

[daylighting]

I've heard a lot of growers have had success with 20/4, and I think if I try it, I'll ramp the time down 10-15 mins a day to hit 12/12 (or even 10.5/13.5 for pure landrace sativas).

 

[Hash Zeppelin]

^you can do different things with different light schedules.

For instance if you want a fast flip into flower mode you use a 24 hour light schedule then flip to dark for 24 hours then on to a 12/12 schedule. This can be stressful for the plant though, so if you notice your plant stressing easy or a slow in growth then switch is over to a 20/4.

If you would like to run very low stress and imitate nature start your seeds and clones on 18/6 like spring hours, then move to 20/4 to imitate summer then back down to 18/6 then on to 12/12. you can even more transitions times too. like 16/8.

 

[MEnSouRdeeZ]

View Image

EDIT: the PAR curve on the second pic is skewed too far to the right, but you get the general idea.

good call man that whole picture is bunk. pls no one go out and buy any blacklights ha

I am trying out ushio hps 600's supp. with mixed t5 ATI true actinic and arcadia d3 12%. Waiting for LEDs to catch up they are not supplement worthy yet becuase im not willing to friggin solder however 660nm leds have come a long way...

 

[DinosaurCocks]

i made the switch a year ago and i am loving it! i will never ever ever go back...well except for right now...i am running a 600w hortilux eye hps, because my shop couldn't get ahold of a 600w mh bulb, they didn't even have any conversion bulbs and it was a sort of emergency...but i'll be switching back to metal halide soon, probably within a week, because i just can't stand hps...

i notice better yeilds, more triches, faster ripening, and better smell after switching from hps to mh, and am similarly disappointed since switching back to hps. the biggest, and by far the most important difference for me is the color of the light, mh is much more natural, it doesn't look funny shining through a crack in a curtain, and it doesn't make the plant look like some brown purple alien with 100% amber triches... hps light is red and gives me a headache, makes it impossible to get an accurate amber trichome count...

the difference between the two bulbs is small in my experience, sativas like mh more than indicas, they both benefit from the switch but sativas benefit more. i would say that the max increase is no better than 10%, for me it's not so much about the growth of the buds, but the look of the light. it's aesthetic, although it proves practical when i need to break out the 30x jewelers loup.

 

[shokdee]

Trivia question: Which strain of cannabis is named after the type of lights it was grown under?

High Pressure ... what?
Compact Floro .. who?

Answer: Ezah latem

 

[daylighting]

Cool stuff shokdee! I'm running a 400W HPS now, but looking to pick up some MH bulbs. My first grow, I ran 400W of MH with 150W of HPS on the dealer's recommendation and had great results, although I didn't get to take that grow (NL X Shiva, I believe) all the way to finishing.

 

[elanius]

this is great thread i must say, thanks for the information! After some reading i decided to get 400w Sunmaster Warm Deluxe. But the problem is, it can not be bought in Europe. Does anyone know why? Is there some substitute for this lamp? Sunmaster offers many MH lamps, but only one of them can be bought here. Wtf?

 

[unthing]

quess they think that there's no market here, lot of stuff not available..but those expensive 315w cdms are available in europe if you wanna take a look at that sort of thing.

 

[elanius]

so you are right, these bulbs are not ment for European market. I have done some research (and it was pain in the ass!) but decided to buy phillips 400w hps retro white. From the cmh lamps, this one seems to be the best. Time will tell. Anyway, i will be ordering from USA, this type should work on HPS ballast and thats a good thing hehe

 

[whazzup]

you mean the lamps they are discontinuing in favor of the new greenpower 315 (CDM Elite Agro)?

yes, unlike what philips announced in November last year at the Hortifair they are going to sell the agro lamp in Europe as well. Check also the CMH thread. I would advise you to go with that as in the long run that would be a more safe investment.

 

[elanius]

I thought about that too, CDM 315 can be bought here in Europe, but only the bulb is 84 euro. The CMH retro white 400w is 49 euro included shipping from USA plus i can use it on my 400w hps ballast, unlike the CDM 315...

Yes, they are being discontinued, but:
"The reason from their side is purely commercial market, IE they sell this as a commercial lamp and not as a horticulture/aquarium/commercial Lamp."

So its not like they are defective, i have seen some nice grows with it and no complains. Anyway thanks for the advise, i will definitely consider it for the future runs...

 

[daylighting]

That retro white looks pretty cool.

 

[vapedg13]

here's a few pics of my latest all MH grow using a $21 1000w sylvania BT56 bulb

View Image
.
View Image
.
View Image
.
View Image
.
View Image

Shit is lookin dank bro .......the MHs kick ass they always will out preform hps

People can show me all the light graphs they want.... I go off 20 +yrs personal growing experience and what I have seen with other people grows, who have started out using hps then we switch over to all mh

A mh bulb in the 4000k rage will work perfect for the entire grow for almost any strain

 

[vapedg13]

i havent noticed any differences in potency using mh bulbs.. i actually think my hps yields more and is more potent..

hahahaha that's a good one.....Potency is genetic...lights will not polish a turd

 

[the gnome]

show me all the light graphs you want-> I go off 20 +yrs personal growing experience

show me all the light graphs you want-> I go off 20 +yrs personal growing experience

Shit is lookin dank bro .......the MHs kick ass they always will out preform hps

People can show me all the light graphs they want.... I go off 20 +yrs personal growing experience and what I have seen with other people grows, who have started out using hps then we switch over to all mh

A mh bulb in the 4000k rage will work perfect for the entire grow for almost any strain

thanks vape,
well said and your 100% right!
the proof is in the pudding

I'm doing a sho-n-gro in the mosca forums.
i just made another neat discovery stacking my $21 Mh against a $100 super HPS horti eye to see if it had an effect on ripening in the last 2 weeks of bloom,
it did, there's a BIG difference!


I think its worth posting in this thread as well.
---------------------------------------------------------------
hey grassroots!
i just posted my auto flusher here, post #53

ok,
most of you know ive been using Mh in bloom,
last year i was trying hps and mh and thought the hps may have ripened the buds a bit sooner
so! after flushing the soil 2 wks ago i put an hps super eye horti in one of the hood in this grow,
under it is 5 IBGs and 1 TF

under the MH hood with the $21 bulb is 2 IBGs and 3 TFs.

here are the results....
the pics aren't the best.

here is a pic of the lone TF that was under hps, its in the forefront, the 3 green budz and in the back ground are the other 3 TF that were in MH, the leavves are flushing out chlorophyll like crazy and I'm getting purpling in the flowers.

another wider angle, its hard to see but the TF in the front that was under the HPS is still very green, absolutely no coloring while the plants behind the HPS TF have noticably yellowed out.
its a much more stark contrast in person,
the pics isn't quite getting the stark difference.

another angle of the above pics,
HPS TF forefront-left

this is 2 TF that are under MH, flushing out.

its the same under the HPS hood,
the 5 IBGs are green as can be but the two that were under Mh have yellowed/flushed out big time
i have no idea why HPS is greener and Mh is so far ahead in the finishing process?
.

I have a pile of 1000w HPS bulbs... anyone want them?
pay the freight and they're yours

 

[daylighting]

Fascinating, it seems a certain wavelength (or wavelengths) of light are involved in plant ripening, and HPS isn't doing it.

 

[the gnome]

Fascinating, it seems a certain wavelength (or wavelengths) of light are involved in plant ripening, and HPS isn't doing it.

yes it is to me also.
when i started using Mh in my 2000w grows at the beginning of this/my thread last summer,
I used 1 hps and 1MH
to try to get resin production up with the Mh.... thats when i saw many things that didn't
line up with what I've read with regards to getting superior results using HPS in bloom with some of my strains.

seeing the differences at that time, one of them was I thought HPS may be better/quicker for ripening over Mh based on 1 strains observation.

NOW!
in this current gro, i have 2 strains from seed.
and when i added the HPS under 1 of the hoods in the last few weeks of bloom to see how it performed against the Mh in the other hood in the ripening process.... plants from each strain were under both spectrums...

and it was the Mh that killed it in the ripening process with regards to time framed for.... BOTH strains.
Mh killed it in a HUGE time frame difference,
HPS buds were just starting to yellow out as the Mh buds are close to being finished

check out post #123


pics.... they don't lie