Ceramic Metal Halide (CMH)

[kronik]

Optimal Light Distance for a 400w CMH bulb?

Optimal Light Distance for a 400w CMH bulb?

High all, I'm on my first grow ever using a 400w CMH bulb, thanks mainly to this great thread which I've been reading since the beginning. I've seen the question asked a few times but never really stumbled upon a definitive answer....

What is the optimal distance for a 400w CMH bulb from the plant canopy?

I'm currently running mine about 6-8" from the tops and it seems to be doing fine.. however, to add a complication,

I am about to go away for 5 days so I was wondering how high should I raise the light before I leave? Is there a distance that would be too far? I just flipped the switch to 12/12.

Here's a pic of my setup... I'm growing HGS Black Pearl and Monster Bud in the Moonshine Mix:




Thanks in advance and a big thanks to all the great posters of this thread who inspired me to start off growing right - with a CMH bulb!!

kronik

 

[FreezerBoy]

Not familiar with your strain but, many take off at the 12/12 switch. Stretching out, assymetrical stemming, all that jazz. I'd give them at least a foot for a week long vacation. With your cab and space (assuming pic is current) I might even raise the lamp to the top of the cab. Yeah, that's paranoid thinking but, better a little extra stretch trying to find strong light than to find all your growing tips burnt to a crisp.

Do yourself a favor. Measure your plants now and when you get back and write it down in a journal. Next time you won't have to guess. I used to keep all that stuff in my head, like phone numbers and bank balances. Not anymore, I need to write it down.

 

[Guest]

kronik, how close is the lamp now? When you put the bottom of your wrist even with canopy is it HOT? How close can you get the bottom of your wrist to the bulb befor it's TOO HOT?

I think that this is a good way to determine how close is good. Am I wrong here?

 

[Guest]

If I am doing a vertical grow, even though the bulb will be hanging vertically, do I still want a horizontal bulb? The reason I ask is that if the vertical bulb is designed to throw light down, then I don't want that.

THis Q is unanswered Simba. This info is need. Also, is the vert bulb a base up or base down or does it matter as long as it's vert?

If the bulb "throws" heat down witht the base up could you just go base down and vent above light?

Das.

 

[FreezerBoy]

We answered that one months ago. Vertical bulbs for vertical apps. Horizontal bulbs for horizontal apps. Bulbs will work in the "wrong" direction but at the cost of lifespan. Lamps, regardless of the direction they hang, throw light perpendicular to the shaft, not parallel.

Base up or down? The standard way of using them in industrial situations is base up. If they were used base down, factories would have to line their entire ceilings with reflective material or lose all the light in the rafters. This isn't to say that base down wouldn't be better for us, just that, I believe, base up is "standard."

 

[a6grow]

sorry if this is a newbie Q, but I did a search and couldnt find a definite answer. anyways here goes:

for CMH I plan to go with a 150W bulb, am currently looking to get the ballast, but had a question. if I get the proper 150W ballast for CMH, would a 100W CMH bulb work in the same ballast as well?

reason being that I have a micro grow and I was thinking that for the summer I will want the temps as cool as possible and will use a 100W and for the winter I will switch to 150W for a little extra heat. obviously I want to just purchase 1 ballast if possible. please let me know guys. thanks!

 

[FreezerBoy]

Look up the bulb you want and check the ANSI code for the proper ballast. The bulbs you've selected require different ballasts.

 

[simba]

dasme..
yes the cmh throws less heat vs hps.. however you cant compare that big of a dif..
id say a 150 cmh would run as hot as a 100 hps..

thanks FB for chiming in on ur setup i was trying to find the link to ur frow log..

gramsi.. did u let ur buds dry totally.. thats a big thing.. (cures the THC(
i haven't noticed decrees..in potency that would be a negative.

Kron, depends on setup.. close as 1" (with proper air cooling in hood and air over plants_)
id raise about 2 feet from where it was in the pic.. (just to be safe. )
better safe than sorry.. (if the plant grows into the lamp phhh.. but if only stretches a bit. its not as bad.)

dasme, vert is base up or down.. Pref Base Up..
the heat comes off the lamp verticly no mater what burning position (vert or Hor)..
Yes u could cool from bottom up... (air coming in from bottom and exhausting up)

a6grow, nah u cant go diff watts to diff ballasts.

 

[a6grow]

thank u FreezerBoy and Simba.

 

[Guest]

dasme, vert is base up or down.. Pref Base Up.. the heat comes off the lamp verticly no mater what burning position (vert or Hor)..
Yes u could cool from bottom up... (air coming in from bottom and exhausting up)

So the bulbs throw heat out the ends or just heat rises faster that the bulb throws, so it never makes it far from bulb. Noob Qs, just want to make suer I get the right bulbs.

Bulbs will work in the "wrong" direction but at the cost of lifespan.

Simba, is this true, and how much loss of life are we talking here?

Lamps, regardless of the direction they hang, throw light perpendicular to the shaft, not parallel

So then this isnt true. Not calling you out, just clarifying.

 

[fideralala]

What in your opinion is the advantage over HID-Lightning (except security reasons)
I still dont get it.

 

[gramsci.antonio]

gramsi.. did u let ur buds dry totally.. thats a big thing.. (cures the THC(
i haven't noticed decrees..in potency that would be a negative.

yeah yeah i say this 4 months after the crop... actually i'm out of weed...

the fact is that a foaf grow the same plant (DP PP) and his is slightly stronger... he used neon in veg+hps in flower...

but maybe it's just the normal seed fluctuation...

 

[blueberryfarmer]

Okay I've read a bunch of this thread (not the whole 116 pages!) and I have a couple of questions for clarification:

1. I have a 250-watt HPS ballast (dont know much about it) - my understanding is that a 250 CMH bulb will work with this no problem, correct? Are there any possible problems I might have (socket size maybe)?


4. Is there any reason anyone might NOT want to use a CMH bulb to grow? From everything I've seen, there are only pros and no cons... there's gotta be something!

Thanks!

 

[simba]

Gram.. (to gram and others..illl respond to pms tonight sorry for delay)
ya that must be crappy seed.. (can u get a clone of his)
that kinda sucks to go threw and have bunk genetics (the joys of picking out a good Mummy)..

Blue..
1. Yes ur are Ok to run HPS Retro White CMH in a HPS ballast..
2-4 are in a pm to u.. and others will chime in im sure..
4. None that i found.. (however i do think the spd can be tweaked a bit.. (ditch the green spike and put in Red.. (harder than we want)

 

[kronik]

Thanks for the replies guys about my post about optimal light distance... I am currently running about 4-8" away and it's cool as a cucumber... current growth is about 1-2" a day max so I am thinking I will raise the light 12" from the tops which should be safe for a 5 day trip.

I just flipped to 12/12 and I read that slows/stops growth for about a week and then it really takes off so hopefully that is true as that would suit me just fine.

Check out these pix of my very first grow using a 400w CMH, the Moonshine Mix and HGS Black Pearl and Monster Bud (MB are the 2 up front).

Sun Jun 22 - I was obviously experiencing a nitrogen deficiency:



1 week later, Sun Jun 29 after watering with a FoxFarm Grow Big and Big Bloom tea:



All I can say is DAMN!! I love FoxFarm and I love my CMH

kronik

 

[blueberryfarmer]

Thanks a lot for the quick reply simba!

 

[FreezerBoy]

Not calling you out, just clarifying.

Call away. If I have broccoli in my teeth, I want to know NOW not at the end of the day.

I admit, there's a point that electricity simply becomes voodoo to me. As I understand it, hor and vert designations aren't about light direction but, polarity. The lamp is set to arc in a particular direction. Hanging the bulb "wrong" means the arc can't find it's proper destination in the proper place so it has to work harder to find it. If the bulb that burns twice as bright burns but half as long, so too the bulb that works twice as hard.

HID works almost opposite to a flashlight. Point an HID at the wall or floor and it throws a black spot. The reason the flashlight throws a light spot forward is, it's set into a cylindrical reflector that redirects the light. An umbrella reflector will do the same for a vert CMH. Unreflected, the vert CMH would be used in a vert ScROG or Stadium/Coliseum where it throws light to the sides in all directions but little straight up or down.

If any can show that this is incorrect, then smack me silly and then let's get the correct info on the first page because I thought we'd already determined this. Whatever the correct answer is, lets lock it down and list it upfront.

 

[FreezerBoy]

What in your opinion is the advantage over HID-Lightning (except security reasons)
I still dont get it.

Check out the first page. Bluer than MH, redder than HPS, lower temps, one bulb, one ballast. What's not to love?

 

[messn'n'gommin']

I am curious to know other's initial thoughts and opinions of this reflector, especially Simba's. It is designed specifically for aquarium halide systems, but I can see definite applications elsewhere.

http://reefkeeping.com/issues/2008-06/review/index.php

Namaste, mess

 

[gramsci.antonio]

Call away. If I have broccoli in my teeth, I want to know NOW not at the end of the day.

I admit, there's a point that electricity simply becomes voodoo to me. As I understand it, hor and vert designations aren't about light direction but, polarity. The lamp is set to arc in a particular direction. Hanging the bulb "wrong" means the arc can't find it's proper destination in the proper place so it has to work harder to find it. If the bulb that burns twice as bright burns but half as long, so too the bulb that works twice as hard.

it's an allineation with the earth magnetic field.

The electron flux has to be parallel to the magnetic field of the earth, in order to use his strength to accelerate the electrons, rather than make the electrons move AGAINST the magnetic flow.