Hi everyone,

I'm thinking about getting a 250w MH to combine with my 400w HPS, as I've heard that Hazes love MH.

I was looking at possibly getting a Cooltube, but spoken to a friend who told me that a glass casing will filter out the UV from the MH, which is the main reason they rock.

I've read around a bit, and apparently you can get quartz covers which don't filter out the UV, but I can't see any for sale on Greens... so I guess they're not used generally?

So is it still worth getting a 250 MH if I use it with a Cooltube (I don't think I could deal with the heat from anything else) or should I stick with just HPS?

Cheers!

AFAIK MH lamps already have a quartz envelope on them which attenuates UV.

Hmm, so in that case the light from the MH isn't disadvantaged further by the additional glass layer on a Cooltube?

AFAICR MH lamps still allow a *really* small amount of UV through the envelope, and I guess that this could be attenuated still further by glass, but I would have thought that the amounts are so small to start with that the overall effect would be negligible.

If you want to experiment with UV supplementation you're probably much better off looking into using those reptile lamps - there's some really good threads on here about it all.

Ahh interesting, thanks man

mmmm that lead to a couple of hours of very interesting reading!

I think I'm going to pick up a 60w UVA/B lamp and try giving my plants a few hours a day to see how they like it

Thanks!

Hey mate i was bangin about uv/b too but still didnt get my hands on it ,here is few threads that got me interested in it.


http://www.uk420.com/boards/index.php?show...=103161&hl=

http://www.uk420.com/boards/index.php?show...=147865&hl=

http://www.cannabase.com/cl/bcga/bcga/uv.htm

Some important things:

If you are going to play with UV emitting lamps, UVB is the key one (same as reptile lamps), you will want to get a UVB meter to measure how much you are dosing your babies. Protective eye gear and clothing (long sleeve shirts, heavy gloves) are a must to help prevent cancerous tumors from developing.

Likewise you can also carefully break the glass envelope for your MH to produce more UV. Same hazards as mentioned above apply.

quartz passes uvb, and partially to uvc, the inner tube is quartz, because it has to withstand the temperature of the arc, the outer envelope is glass, which is opaque to uvb/uvc, but may pass a very small amount of UVB, UVB lamps have doped quartz outer envelopes to pass uvb and filter uvc. uvb attacks the quartz, and overtime the quartz becomes opaque to uvb and also normal light, which is why MH lamps have such poor lumen maintenance (go dimmer quicker)

don't be doing that rand, metal halides give out a fair amount of UVC without the glass envelope! uvc will seriously affect your plants likely kill them!! anyone who welds will know what uvc burns feels like, it's not pleasant believe me. it's like sunburn but feels like being covered in wasp stings, don't even want to think about arc eye i've seen where people have done this, but it's fucking stupid and very very dangerous. on a lighter note, uvc is known as germicidal uv, so you wont have any mold or plants viruses

as for the reptile lamps, depending on the type you get, you shouldn't have to worry to much about glasses and gloves and all that but it depends on the lamp you get, those mega rays can be mighty powerful, but most are designed for use around people and only give off the kind of levels of uvb that would give you a tan at a few foots distance, uvb is rapidly absorbed by the air, which is why we don't receive dangerously high levels from the sun (well not all the time anyway specially in frikkin blighty!!), this alongside with the inverse square rule means reptile lamps are only effective over reasonably short distances, you should get a light map with a reptile lamp that'll give you a fairly good idea of uv levels at whatever distances, no need to fork out on a uvb meter, unless you really wanna push it to the edge

Thanks Herbal! I'd read two of those but missed one, so v. useful

Yeah Randalizer, I was thinking I would just make sure the UV lamps were off when I was doing stuff in there, but I'll pick up a pair of sunglasses too, just to be on the safe side

And cheers scraglor, you confirmed a few things for me with that post

scraglor is the man.