Your question actually needs more questions answered to determine a
good choice for your use.
Such as: You say a 5x4 space. How tall? You need good head room for a
HID light.
Is this room enclosed? If it is you should probably get a fixture that
has the ballast separate from the lamp so you can put it outside of
the grow space. (the ballast that is)
What is the humidity in the grow space? If you are running humidifiers
and it is 70% or more, you want to look for a fixture that is enclosed
and has a glass cover over the bulb and socket (you do not have to but
the life of the fixture will be greatly reduced by the high humidity,
as well as becoming a possible fire hazard as the wiring and socket
corrode) I have gone so far as to use RTV glue on wires, screws, and
the ducts on the reflector.
How hot is it in you grow space? With 3 sets of florescent fixtures in
there all ready each of those has a ballast in it, so you are all
ready pushin the temp up (unless these are the solid state kind, still
they are producing some heat) So you may need to get a fixture that
has duct work attachment on it so you can vent the heat out of the
room.
One word on this is: run the duct work from out side the room into the
fixture and then out of the fixture to the out side of the room.(Cause
if you just run the vent out of the room then the air goin in to the
fixture would be the moist air in the room and thereby defeat the
purpose of having the fixture sealed from moisture!)
There, that should have confused the issue a little more.(not that i
am tryin to) It's just that there are a lot of variables depending on
your pref and situation.
One other thing you may want to consider is high pressure sodium
instead of metal halide. The HPS is slightly better for flowering,
although I have had excellent results flowering with just MH on some
stuff. You need to decide that because the ballast is made for one
type or the other (some are made to be switchable and there are some
conversion bulbs that let you use a MH bulb in a HPS system)
There are a couple of hoods that have a socket on each end so you can
run one bulb of each type in the same fixture.
Go to the pot and hydroponics news groups and luke in there to learn a
whole lot about lighting. Just remember that if you post in those NGs
all posting are sifted by your friendly feds! Also if you go to a
hydro store and purchase, use cash. (Yeh I know "your just paranoid",
Damn right I am!) I used to be a guerilla farmer of pot outdoors and
indoors many years ago.(when I was yung and stupid, I found out the
hard way) Believe me they do go after innocent people with just as
much venom as the guilty ones.
I have rooms for propagation of seeds and rooms with seedlings as
well as extra lighting in my sun rooms and holes knocked in the back
wall of my house for outside ventallation.Plus a network of 10
computer throughout my house. If you thermal image my house, it looks
like a giant ball of red!! I have nothing illegal in my house, no
kiddy porn on any of my computers (I run S.E.T.I. on them 24 hrs a
day). Because I know that one day the cops are going to come to my
house salivating thinking they hit the mother load of a grower. When
they find out it's just orchids they are going to confiscate any and
everything to try to come up with some kind of charges to justify
busting in my door!!! I do have several boxes of old High Times issues
in with my vast comic collection and I have been thinking lately I
should probably get rid of them to. (sad that you have to be paranoid
even though you are doin nothing illegal!)





On Thu, 28 Aug 2003 14:03:26 -0400, TS wrote:

My basement indoor space is 5X4, and I recently added a shelf (3 tiers)
with 2 double florescents above each shelf. I want to add a 400 watt MH,
hung from the ceiling to add more light (and grow some other taller
plants- like Hibiscus). I figure that the lower light orchids can be on
the lower shelves, with the high-light lovers on the upper shelves
closer to the MH.
My question is about the MH light itself. I have been searching ebay,
and the web. What should I buy? There are many different types:
Industrial hi-bay types
Grow lights like Hydrofarm
Cheaper Grow Lights w/ batwing reflectors
Flood light fixtures
Etc.

They can be bought used, refurbed, or new. And there is a huge price
difference amoung the different types. Obviously those Hydrofarms are
the best, but is it worth the extra money?

If anyone can recommend a type of light, or share experiences I would
greatly appreciate it!