Ceramic Metal Halide (CMH)

[Geoffrey Boycot]

any advice on a reflector for a 400w CMH in a 6-9ft grow area? Is a sun system 2 too big for a 400w?

currently deciding between CMH & straight MH for the sole purpose of vegging.

 

[bbspills]

I'm about to start my second scrog and will use 5 plants at 1 per sq/ft again. What pot size should I use? My last scrog used 8" pots which are 3 quarts and I was thinking of moving to 10" pots which are 6.5 quarts or even 2 gallon pots. Are these pot sizes overkill for a scrog with 5 plants at 1 plant per sq/ft?

 

[messn'n'gommin']

any advice on a reflector for a 400w CMH in a 6-9ft grow area? Is a sun system 2 too big for a 400w?

currently deciding between CMH & straight MH for the sole purpose of vegging.

I've never used a SS2 so I can't say if they are or are not.

But, I have yet to hear any serious complaint of CMH used for veg. As a matter of fact, even those who have little to say about them for flowering, concede that the CMH is far better than MH for veg. Something to chew on.

I'm about to start my second scrog and will use 5 plants at 1 per sq/ft again. What pot size should I use? My last scrog used 8" pots which are 3 quarts and I was thinking of moving to 10" pots which are 6.5 quarts or even 2 gallon pots. Are these pot sizes overkill for a scrog with 5 plants at 1 plant per sq/ft?

Just my ...but, going to a bigger pot would allow you to go with a longer veg and, in the end, a bigger screen. But, that would make for fewer plants in the same given area. If soil and a 2 gallon pot with a bigger screen, maybe three or four plants?

Namaste, mess

 

[Geoffrey Boycot]

I've never used a SS2 so I can't say if they are or are not.

But, I have yet to hear any serious complaint of CMH used for veg. As a matter of fact, even those who have little to say about them for flowering, concede that the CMH is far better than MH for veg. Something to chew on.

thanks for the input. I have no practical experience of either, but i'm struggling to see past the 6500k of the MH vs 4500k of the CMH. Why do i need more red in vegging?

the only thing that may sway me back is the reported reduced temp of a CMH vs MH, but im not certain how confirmed that is. 400w is 400w and the lumen/photon output difference isnt enough to account for a major heat difference is there?

thanks again
Geoff

 

[messn'n'gommin']

thanks for the input. I have no practical experience of either, but i'm struggling to see past the 6500k of the MH vs 4500k of the CMH. Why do i need more red in vegging?

the only thing that may sway me back is the reported reduced temp of a CMH vs MH, but im not certain how confirmed that is. 400w is 400w and the lumen/photon output difference isnt enough to account for a major heat difference is there?

thanks again
Geoff

With the sun at about 5500K some red is a good thing. I would think of it more in terms of a "balanced diet" (a poor analogy, I know). But, all things being equal, it works out well. It is, after all, a MH at it's core, so it will still have plenty of blue. I think (a very subjective opinion), that is where some of the controversy comes from concerning the HPS aspect of the lamp. More blue than is traditionally considered for flowering, so it keeps the plant a bit shorter and produces more leaves to soak up as much of the broader spectrum as possible. But, at least to me, the quality of bud is better.

It does burn a bit cooler (not much, but somewhat so) and lumen maintenance is a lot better than MH. More than off-setting the initial cost of the CMH over a generic MH.

Don't get me wrong, MH does the job well enough, but, then again so do fluorescents. T-5's (or overdriven T-8's) will burn cooler than either MH or CMH and at less cost.

Namaste, mess

 

[Mr.Meds]

CMH is much more efficient than HPS and runs considerably cooler, allowing you to place your plants closer to the bulb. I have witnessed that side by side first hand. I would never buy another MH after using CMH. They're cheap and can be used for or to supplement bloom if you have or want to....

400w is 400w and the lumen/photon output difference isnt enough to account for a major heat difference is there?

all 400 watt HPS/MH/CMH are not made equally (well not many companies make cmh so not so much for them(would only suggest phillips))
The lumen output increase in CMH is significant because not only does it have more lumens but it has more USEABLE lumens. The PAR watts of a CMH are of greater value compared to a standard MH. It also has a wider spectrum which IMO is more natural.

 

[Pinball Wizard]

I light bleached my two plants...week #3 flowering.. with a 400 CMH....

Two other grows ...no problem?...can't believe I did that..

I was too close.

 

[Mr.Meds]

ouch! too close indeed!

I have noticed that during bloom if you put an HPS on each side and a CMH in the middle, the plants will lean towards the CMH.

 

[Geoffrey Boycot]

CMH is much more efficient than HPS and runs considerably cooler, allowing you to place your plants closer to the bulb. I have witnessed that side by side first hand.

I'm not trying to be difficult but that's what i'd expect if you put your hand near a 4500k light and a 2000k light. One is pumping out hot red light, the other is pumping out cool-er blue-ish light. Did you put your hand near an MH too?

I take your point about bulbs not being made equally well though. If i go MH i'm going hortilux blue. I just struggle to see how a Phillips HPS conversion bulb (for thats what it is non?) can beat a MH bulb designed specifically for vegetative growth. If the 4500k was more useful for vegging than the 6500k then why wouldnt hortilux have designed their vegging bulb to hit 4500-5500k...its not a technically difficult task.

Do you have the PAR rating for Phillips CMH v Hortilux Blue you mentioned? I havent seen those figures. I saw some PAR figures for CMH vs other bulbs and it didnt win.


Thanks again for your time & input
Geoff

 

[MrBomDiggitty]

I'm not trying to be difficult but that's what i'd expect if you put your hand near a 4500k light and a 2000k light. One is pumping out hot red light, the other is pumping out cool-er blue-ish light. Did you put your hand near an MH too?

Uh, isn't red cooler and blue hotter? I know on 3000K CFLs the temp is lower than on 6500K CFLs.

 

[Geoffrey Boycot]

I think you're right. It requires more power to emit blue light than red light so the object gets hotter in the attempt. (ie as something gets hotter it starts to emit more blue light)

I was thinking that as red is closer to the infra red part of the spectrum (ie heat) and blue is closer to the uv part of the spectrum the red would be hotter.

MnG's thoughts of lumens maintenance was valuable as well re: CMH. Maybe it really is a more efficient light. Why has no-one other than this message board heard of it/done trials?

 

[Mr.Meds]

If in doubt, buy both and see for yourself. That's what I usually do. I find CMH to be all around more convenient...

 

[Mr.Meds]

with the exception of having to buy them online

 

[Geoffrey Boycot]

If in doubt, buy both and see for yourself. That's what I usually do. I find CMH to be all around more convenient...

yup. looks like its going to have the be the switchable MH/HPS ballast for me. I WILL find out the bloody answer to this!

 

[MrBomDiggitty]

I havent run any side by side trials, but they work good for me, veg and flower

 

[stink.whistler]

Finally a seller on ebay for this lamp... anyone used this seller? $49 shipped is the best I've found... He also has GE S51 Ballast (which he claims are better than Howard...) + CMH + Mogul base (which I had to buy separate when I used advancedtech, they failed to mention) for $114 shipped...
Pls share any experiences!

Actually, advancedtech is very clear w/ regards to what comes with their ballast kit (which is less than half the cost of the ballast on the ebay ad) - and they sell a mogul base for six bucks.

I wouldn't buy that ebay ballast for 2x the price, personally (the seller has one feedback in the past five and a half years, by the way).

 

[MEnSouRdeeZ]

The ballast comes with the philips lamp and the mogul socket. Its a better price and Howard industries is hardly the reputable name GE is

 

[stink.whistler]

You are correct, I didn't notice it came with the bulb too. Let us know how you like it, if you buy it. (Howard Industries is a perfectly reputable company, not the household name GE is, but a decent company, none the less)

 

[Mr Celsius]

I always come check in on this, but do they have 1000w CMH yet?

 

[Mr.Meds]

I always come check in on this, but do they have 1000w CMH yet?

No...I called them up and asked them why they were making such slow progress and they said that they have been in an intense game of cornhole ever since designing the fours.