CAUTION: CMH (Ceramic Metal Halide) light dangers.

Many of you that have been considering switching to CMH lights should take to heart the warning about the UV radiation that these bulbs emit. I have just installed this light in my 400w hps(magnetic of coarse) ballast.

Well, today i spent about 10 minutes under the normal HPS bulb, as usual. Today i forgot my sunglasses which i try to use but often forget. No adverse effects before. Later i installed the new CMH bulb and proceeded to water my plants. Total time under light was less than about 5 minutes again. Well after the 5 minutes my eyes were feeling stressed, similar to a day at the beach without glasses. After feeling this i went and got my sunglasses and continued my work.

Now, around 4 hours later, my eyes still have a slight sting as i feel i soaked up a little burn in this very little time.


So just a little cautionary story, if you are considering a CMH Bulb just make sure you use sunglasses(even more so than hps and mh) and a long sleeve shirt/gloves isnt a bad idea. These bulbs are hot start rated, so i imagine turning off your light before entering the room shouldn't be too much of an issue. I would treat this light as you would with the harsh UV lights out there.

Be careful.

good information always safety first +REP

I know what youre sayin dont go in the first thing when you wake up or you will really feel the pain. overall its a great light, the ladies couldnt be happier.

I will need to give it a few days or a week or so i imagine to see how the girls react. I imagine mine will react very well as they are still in veg, and veg with hps (cheap bulb at that) is nothing to write home about. How long before you noticed the change? or did you start with CMH?

Back on topic, my eyes now feel better. But it took nearly 6 hours to recover. Never mind the short term pain, with continued exposure this light(at least at these distances) could cause some severe eye and/or skin damage. On a side note i checked on the ladies with glasses on from the beginning this time, no ill affects. Though i would still consider turning off the lights during inspection/watering/working.

Also thanks for the rep dapio

could i tan under my cmh? haha just kiddin. ill wear long sleeve and sunglasses when ill have my cmh. extra bonus, ill look cool gardening

I started with 150mh to veg. Im 3weeks into 12/12 and sugar sugar baby i might run out of room too. I think these bulbs are the way of the future people dont use em cause you can only get em in 250 or 400 honestly i think any higher than 400 or 600 is dangerous.

I will be supplimenting this(or rather visa versa) with a 600w hps. It will raise my grow area to around(or above) 10,000 lumens sq/ft. pretty excited for that

I doubt these bulbs produce much if any UV radiation. UV is in the far blue spectrum. I just have a hard time believing these bulbs can get in that range. I'm not calling you liar at all (I hope I don't seem like I am), I'm guessing you're being a bit paranoid is all. I could see you having a sensitivity to that spectrum of light in terms of creating eye fatigue. Being under or looking at any intense light for very long (even 5 mins is considered long) is enough to make anyones eyes feel out of whack.

If these bulbs produced much if any UV radiation then there should be a warning on the box. Not only would they put you at risk for skin cancer, but they would do the same for your plants too. Yes shockingly plants can get skin cancer too, I know this sounds stupid but its totally true. Thats a worry for Australia's plant harvest since they still have a whole in their Ozone layer.

im not calling anyone a lier i have been useing a 250w hps(eye hortilux), a 250w cmh( philips) with a uvb20 (for one hour a day) for a while now im in and out in about 5 mins as well and have never had those problems maybe cause im operating 250's but i will be cautious and pay attention to warning

my plants seem to love both lights i run them together and i spin pots every day and i rotate opt position under lights so all plants get both

if i notice anything to report on the light i will inform RIU comunity

we are all in this together
keep em green
1Luv

It depends on what bulb you buy, one has UV block added in and others dont. I will have to look up which is which, but perhaps you should not make blanket statements(nor should i).


EDIT: Btw plants can and do use UV light. Too much can cause adverse effects, but supplementary uv light is beneficial when used right. Check out the research done by some of the members regarding a 13-15 hour flowering cycle utilizing UV supplementation.

Edit x2: Also note that just because you cant feel the radiation does not mean it isn't damaging you. If you are regularly exposing yourself to UV light in intense situations like a UV specific bulb, well we can talk when your 50... if you make it.

edit x3(lol): I do actually have light iris and in general am very sensitive to light(when its bright out i sneeze a lot...everytime) so my experience may be more drastic than others. But prolonged exposure is just not a good idea.

I am liking this light a lot, it dropped my max temps down about 3-5 degrees and the plants seem to love it. I just kicked on 12/12 and am eagerly awaiting the results

Sounds like you had minor flash burn. If you ever wake up at night and it feels like someone poured sand in your eyes it is full on flash burn. The only thing you can really do is apply a cold compress to your eyes wheil they are closed. In extreme cases doctors will perscribed anesthetic eye drops. If it keeps up I would buy some #4 or #5 flash goggles. I thnk Home depot has #5's but you'll have to go to a welding supplier for #4's.

How big is your space karr? I sent you a friend request did you get it?

It is a 400w system. And i have a few friend requests, but every time i try to confirm any of them i my screen never refreshes, it just stays idle.

I will be going home for thanks giving, in about the second week of flowering, i intend on raising my light a foot or more(opinions) to avoid stretching into the light(though it shouldn't be entirely detrimental if it did). Also need to set up a drip water or something similar as i will be out for 4-5 days and my plants seem to like water every other day now.

Thanks for the information and concern on the eyes. It was very mild exposure, all better in a few hours and i have been more cautious since. Next time i have my lamp apart i intend on checking the bulb for the UV designation (weather its blocked or not) so i can determine if it was just the intense light or in fact radiation.

Oh and space is 3x4 roughly.

karr said:

It depends on what bulb you buy, one has UV block added in and others dont. I will have to look up which is which, but perhaps you should not make blanket statements(nor should i).


EDIT: Btw plants can and do use UV light. Too much can cause adverse effects, but supplementary uv light is beneficial when used right. Check out the research done by some of the members regarding a 13-15 hour flowering cycle utilizing UV supplementation.

Edit x2: Also note that just because you cant feel the radiation does not mean it isn't damaging you. If you are regularly exposing yourself to UV light in intense situations like a UV specific bulb, well we can talk when your 50... if you make it.

edit x3(lol): I do actually have light iris and in general am very sensitive to light(when its bright out i sneeze a lot...everytime) so my experience may be more drastic than others. But prolonged exposure is just not a good idea.

Click to expand...

Yes you are right plants like UVB light that guy dosent seem to know what he talking about and yes the buld can do damage to your skin ......

I can tell from the first week(not even full week) that my plants love this CMH bulb over the previous hps(keep in mind i am/was vegging with hps, not ideal). The youngest plant has somewhat exploded, moreso than the older ones.

Once i get far enough along i will add the 600 and we will be in business

How will you keep temp with a 400 and 600 in a 3 x 4? I have a 400 in 6 x 3 x 9 or 8 and im at 75 to 80.

Not sure how your temps are so high with that large of an area. Is it hot where you live? Do you have proper ventilation? With my 400 alone(hps or cmh) it is difficult to keep temps up enough. My outside the room temps stay at about 60(basement) and the outside ambient temps get as low as 39 these days.

In all honesty it really doesn't matter what wattage bulbs you use as long as you have the appropriate air passing through them and outside of your room, i use my exhausted heat to heat my house. Of coarse i am talking of sealed reflectors.

That feeling in your eyes also comes from being really baked, are you sure you weren't just blown?

Different feeling, this was more of a sunburn in your eyes. I have had it before from swimming all day without sunglasses, not water exposure either, just the sun.