Do Ceramic Metal Halide lights actually work?

Depends what you mean by 'work', but yes.

They have a far superior spectrum to standard MH and HPS and bulbs are fairly inexpensive. Luminous efficacy is on a par with standard MH and far below HPS.

CMH may be used for the entire grow as it has plenty of blue for veg and suffiicient orange, red, deep red and far red for flowering.

They generally will not run (with a few exceptions) on digital or electronic ballasts and are limited in size to 400 watts.

 

Two plants is very vague. I have seen 12" bonsais and 12 foot monsters. That plus you have skipped every other parameter necessary to make a proper determination.

If you plan on never expanding your grow space and are growing just enough for personal use, then a 250w will suffice. A 400w will give better yields, but will require much better cooling.

 

I am about half way through my first grow and i went with CMH for vegging. Started with 1 400w for 4 plants switched to 2 for the last week of veg, then i will switch to 2 400w HPS. So far the results have been awesome with the CMH, plants are all about a 15 inches and very dense and a healthy deep green color after about 4 weeks. i also like that the ceramics dont throw as much heat as HPS so its great for a small area. only disadvantage i see with CMH is supposedly a digital ballast will make them fail prematurely, and 400w is the max available.

Now this is only my first grow so i have nothing to compare them to but these babies seem to do the trick, might not cast as many lumens as a HPS of the same wattage but its visibly the closest thing to sunlight you can get with HIDs.

I would say a 400w would be perfect for 2 good sized plants.

 

I cant recall but I believe only certain ballasts can accept them might be wrong though.

 

Since your a new grower I suggest you read all the stickies at the top of the various forums...there posts that dont go away filled with useful information. Google some grow guides and read them as well. You will find after reading 2-3 grow guides they all sound pretty similar. A book to pick up to is Cannabis Grow Bible very interesting read and helpful.

Heres a good guide for beginners I read way back when I started off.

Marijuana Grow Guide | Growing Marijuana | Home

 

Make sure your CMH can be put in that ballast before you buy it. You can also just grow with HPS from start to finish as well.

I think growing bushier and healthier is a better term. It takes cannabis on average regardless of set up about 1 month to veg and 8 weeks to flower sometimes more but usually not less.

 

A 400w would fill that space nicely. Cooling will depend on your climate and exhaust fan size.

HTG has a 400w CMH for less than $200 including bulb, ballast and basic reflector. I am not necessarily recommending it as I have no personal knowledge of it - have just seen it advertised, but it seems to be a cheap entry for a new grower.

With that you should be able to easly harvest 5-6 ounces in less than four months if you can follow basic directions.

 

the ballast will get hotter than the lamp most likely, so as long as that is outside of the tent you should be fine with a small fan. CMH doesnt throw much heat. i can keep them within a foot of my plants easily.

Now there are digital ballasts that work with the CMH but they must mimic the 60hz waveform from a magnetic ballast. Baddass ballasts are the only ones i know of that do this.

 

As far as fans go Id recommend having some kind of oscillating house fan in the tent blowing on the plants to keep stems strong and the canopy cool in addition to an exhaust fan to extract heat.

Digital ballasts will offer you more light output for the same wattage as a mag, usually a 20% increase (although im not sure if this is true for low frequency digitals), as well as producing much less heat and being almost silent. (no 60hz hum)

The only negatives are price and compatibility with CMH.

 

Magnetic ballasts are the way to go if you want to use CMH. Cheap and built like tanks. Some of them can get loud as them from what I hear too, but the 250w I recently played around with didn't/ It is new though.