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Metal halide vs HPS for flowering?

0p0rat0r

Member
I'm flowering with a 250 watt metal halide right now, I'm wondering how much difference it would make if I got an HPS conversion bulb? Will I see significantly improved yields or noticably fatter buds? I think the wattage output drops down from 250 to about 230 with the conversion bulb.

Any of you have pictures of plants flowered under both metal halide and hps for comparison or experience? I know just about everyone uses HPS for flowering exclusively and it has something to do with the colour of light output, but how much difference does this really make?
 

MTF-Sandman

OG Refugee
Veteran
I've got a 2K setup right now with 1K of each over a 4x8 table...

There's a few very minor differences in the buds, but definitely nothing that's mind blowing.

The MH side:

Slightly frostier
Slightly denser
Somewhat shorter internodal spacing

The HPS side

Slightly larger buds (but a hair fluffier)
Plants are a little taller

Since it's a quasi-perpetual SOG, I'm gonna run them the first 4 weeks under the MH side, then move them to the HPS to finish out...



 

DocLeaf

procreationist
ICMag Donor
Veteran
to add:

metal halide put out light from the blue end of the spectrum. this blue light mimics late spring and summer environs when the sun sits high in the sky. this light band is ideal for growing, and ok for seeding plants.

high pressure sodium put out light from the red end of the spectrum. this red light mimics late summer, autumn, and early winter environs when the sun sits low in the sky. this light band is ideal for flowering and ripening sinsemilia

note:

we often force flower in spring using natural blue light, but results usually show more compact buds under hps indoor, regardless of growing/flowering season

hope this helps
peace dleaf :joint:
 
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D

dre86

So after reading this thread I came to the conclusion that there wont be much difference if you give MH (blue spectrum) or HPS (red spectrum) during flowering?
 

MTF-Sandman

OG Refugee
Veteran
Not much difference...even though the MH is slightly less efficient lumens/watt wise, it'll still throw very nice buds. I should note that I'm using Agrosun Golds for the MH and an unknown Eye for the HPS (soon to be replaced). Quality bulbs with a good spectrum seem to do more than the actual type of bulb IMO.

Honestly I was expecting a much more pronounced difference from this test.
 

darrinjefferson

Active member
i was thinking about using my mh bulb for the first week or two of flower to help minimize stretch, then switching to the hps for the rest of the time. kind like what you do sandman.

think it will be a good little test and maybe reduce stretch a bit.

later
 
D

dre86

Well this got me thinking, I have a 400 watt HPS ballast and I just bought a bulb Philips Son T-Agro for growing (vegging) plants....this was meant for my next grow....So it would be good to use that 1-2 weeks into flowering, then switch to my regular bulb?
 

0p0rat0r

Member
I think I'll stick with my metal halide all the way through flowering then. I did some research a while back on OG before deciding on an hps or metal halide and I vaguely remember coming across a couple articles and posts from people saying metal halides put out some type of uv light which has a good effect on trichomes...
 

MTF-Sandman

OG Refugee
Veteran
bounty29 said:
Do MH bulbs put off more heat? That might be something to consider when planning.

It's negligible if you're aircooling the hoods...I can't tell a difference with the hand over canopy test.
 

DocLeaf

procreationist
ICMag Donor
Veteran
good info. all :yes:

to add (again): on the reverse, a hps bulb can be used during veg. and bloom cycles to make nice patterns of growth.
however, we find that trichome content and levels of essential oils are most abundant under levels of red spectrum (indoor or outdoor) rather than blue light during the latter stages of ripening.

big buds is one thing, but buds full of resin is something else, those mh bulbs are also more expensive to replace!

(note: not saying ya buds aren't full of crystals MTF,,, just adding to thread... lol)

peace all
dLeaf :joint:
 
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Brazilian

New member
Hi there everyone, i went to the store nearby and bought myself a metal halide, but when i noticed, the seller asked me blue?? and i said yes blue, but when i got home and tested it, my grow closet is looking like a motel room, i called the vendor, pretty much worried because its suspicious for a guy here buy a 400 WATT metal halide and still mistake i dunno, and i asked if i could change the bulb for another color, white i think...
what do you think guys what color of mh would be the better? notice that i already have a 400 wat hps that i was using until now.... thanx..
 

Homeless

Member
You're fine with the HPS Blue spectrum...I'm sure its a multi-color and not simply all blue.

If you think you'd be better off, then exhcnage it, but I Don't see any problems.
 

Haps

stone fool
Veteran
One light - blue

Multiple lights - first light blue - secondary lights yellow.

Degrade genetic pool - yellow only

H
 
G

Guest

how effective are the agromax bulbs which claim 30 percent more blue spectrum?
 

Closet Funk

CeRtIfIeD OrGaNiC!
Veteran
MH will give you more potent buds. MH put out more UV which makes for more resin. HPS will give you more of a yield though. Both are good. Actually using a full spectrum bulb is best because you get both of best world. Fat frosty nugs.
 

Joe A. Grower

Active member
I used to run a fairly large grow op that used nothing but HPS all the way through from 4" tall clones to 6.5' tall trees. As far as a I can tell the plant does just fine with all HPS. If, as some have claimed, you get "more potent" buds with MH, then I don't want to use it, because the dope I grew using HPS knocked me on my ass! If my weed got any stonier it would probably put me in a coma.

I personally think the idea that MH makes more resin because of more UV is nuts. Even with an MH you still aren't coming anywhere close the UV in natural sunlight. Folks have tried supplementing UV with tanning lights but haven't come up with anything conclusive. If adding a tanning light doesn't make a noticeable difference, I can't imagine how the pitiful UV put out by a MH is going to help.

Don't think I'm against MH, though. I've also used a 400 W MH on a smaller grow. It worked fine, too. I actually like working around MH better because the color is a lot closer to natural sunlight -- much more pleasing to the eye. Under HPS it sometimes gets tough to distinguish subtle shades of green, and photography looks horrible without photoshoping.

Economically speaking, HPS bulbs last about 2x longer, but MH ballasts usually cost less up front. It is kind of a wash. Since the plants don't really seem to care, go with whichever one you like.
 
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BudZad7

Active member
Light as Outdoors

Light as Outdoors

Hi All ! How about a lighting that mimics outdoors......
12 hrs...3 hrs of HPS...then 6 hrs MH...then 3 hrs HPS then lights out...
been using this cycle for 20 yrs...

If you observe your spring and fall lighting outside where you live...that in the
morning the light is that orange glow..(God's HPS light) LOL !!!...then it changes to regular daylight mid-morn to mid day...then back to the late day
to that orange glow of sunset....then lights out..... ;>)

try this your baby's will love it !!! Peace !
 
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dan K

Member
in my personal experiences, i flower with a 400HPS and a 400MH under 1 big reflector....i do tend to notice a bit more trich's and less leaves on the tops under the MH side, but not usuallly a significant difference overall....when harvests r dried and ready to smoke i cant tell the difference it all looks like the same bud.
 
BudZad7 said:
Hi All ! How about a lighting that mimics outdoors......
12 hrs...3 hrs of HPS...then 6 hrs MH...then 3 hrs HPS then lights out...
been using this cycle for 20 yrs...

If you observe your spring and fall lighting outside where you live...that in the
morning the light is that orange glow..(God's HPS light) LOL !!!...then it changes to regular daylight mid-morn to mid day...then back to the late day
to that orange glow of sunset....then lights out..... ;>)

try this your baby's will love it !!! Peace !

:chin:
I've heard this before....It does make sense if you can afford the dual light setup.... maybe I'll give it a shot sometime....
 
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