Metal halide and high pressure sodium lights

[meadowview]

Hi Folks:

Has anyone had any experience with metal halide (MH) or high pressure sodium (HPS) lights in a greenhouse setting? We had one of these lights donated to us and from what I have read HPS is the best light to use in a greenhouse setting where you also have natural light.

I know these lights can explode if you get water on them but how would they handle a general misting/humidification system? Our greenhouse environment will turn into a cloud when the humidifier comes on and I am wondering if this would be enough moisture to blow the bulb?

Look forward to your comments.

Sincerely,

Phil Sheridan
Meadowview

[GregNY]

I have no experience whatsoever with these bulbs, but I believe, depending on your housing of the bulb, that they offer protective shielding to protect the bulb from exploding. I would think, based on your condition, that the bulb could no handle that kind of moisture - not positive though about that - I would just rather be safe than sorry.

I am referring to something like this : www.littlegreenhouse.com/accessory/lights3.shtml

[rsivertsen]

The high wattage, and high intensity HID (mercuric) lamps definitely provides the best light with the intensities of the blue side of the spectrum (including some UV) that brings out the best in our plants (including Aldrovanda). But after several hundred dollars in initial investment, and then faced with an electric bill of over $300.00 for ONE month, (three times the norm) I decided to go back to my shop-light fixtures with a blend of wide-spectrum Sylvania Sun-Stick lamps along with some generic "Gro-Lux" lamps intended for plant and aquarium use, which generally have a blue shift, including some UV in their spectrum. Most Nepenthes and other CP's are fairly tolerant, and will adjust to lesser light conditions. If you can afford it, (or have someone else paying your electric bill), then go for the best that money can buy. - Rich

[Hermopolis]

I use MH's myself. They only explode if cooled rapidly, i.e., the bulb is hot and water is splashed on them. However, they do handle misting without problem. I used them over 8" above an uncovered fish tank where they would occasionally get misted with salt-water and never had a problem. And I know they got misted because of the spots of salt being deposited on the surface of the bulbs. The heat radiated from the bulb will drive most of the mist to vapor before any of it touches the bulb. Plus, the bulbs warm up over a 5 to 10 minute period, so any moisture on the bulb will be driven off during the warm-up cycle. My father used to do electrical for government greenhouses and used MH/HPS lamps without any problems.

The quality/quantity of light is fantastic, and IMHO, much superior to shop lights. And they can be used at a much further distance from the plants than shop lights. My plants (VFTs, Utrics, Sundews, Neps) are very happy under MHs and I am happy with them.

Yes, they are more expensive to run than shop lights, but then again shop lights suck. You need so many of them to get equal PARs what is the point. But I do have to question what rsiversten did to generate a $300/mo electric bill. I run two MH bulbs and it costs me about $12/mo, but then again my compact flourescents cost me about $5/mo. I use 120V lamps/ballasts, but I've heard that the higher power ballasts (277V) are much more expensive to run but also more efficient.

However, rsiversten and I have locked horns on this on more than one occasion. He prefers shop lights. I prefer MHs plus CP/T5s. I think you should try them out and see if you like them, then choose your religious preference.

It may help to know what kind of ballasts were donated to your facility.

[rsivertsen]

Hey Hermopolis, I'm not locking horns with you on this issue at all! It's just that my utility rates are very high in my area! It's even worse in NYC!

Oh well, real life and all, .... Like I said, if you can afford the mercuric high intensity halide lamps, at the highest wattage and all, go for it! It's the best! Otherwise, just improvise like I have done over the years, and deal with it! Life goes on! The plants generally adjust to what you provide, albeit with some reluctance and slower growth. - Rich

[meadowview]

Hi Guys:

This is what I was looking for. The misting system should not explode the lights.

Since we have a greenhouse, my intent is to lengthen the photoperiod during the winter months. So.. I'll have them come on in the morning and evening for a few hours to give more summer like conditions for our hungry friends. I don't need the lights to run all day since the sun is typically shining. However, I have thought of building in a photodetector in the system to deal with cloudy winter days. Anyone have experience with that in this system?

Sincerely,

Phil Sheridan
Meadowview

[meadowview]

Hi Guys:

I checked the wattage on my ballasts. HPS is 1000w and MH is 400w. I'm going to use both HPS and MH to get full spectrum light in the greenhouse. This should be interesting!

Sincerely,

Phil Sheridan
Meadowview

[SundeWCitY]

I have had a lot of experience with HID lighting and honestly the power consumption isnt that bad, I am running 2 400W MH and 1 175 Watt HPS lamp in a small greenhouse and they provide excellent spectrum and colouration to the plants however a few 1000 WAtts would def bring out better colouration ! my problem is getting the lighting to the plants lower on the shelves, the intensity drops rapidly the farther down you go. But i would reccomend them for sure! and i honestly dont think you will have any problems with the bulbs exploding, its a rare occurance! just dont soak the bulbs after all water and electricity dont mix well....coming from experience... ! but yeah id say giver a go!

[SundeWCitY]

i forgot to mention but my lamps are run on digital ballasts , this makes a big difference in power consumption! compared to the magnetic ballasts

[meadowview]

Hi Folks:

Can I get additional comments from you all on under shelf lighting in a greenhouse? I know Rich has already made a few comments but it would be nice to get some more. We have two benches, one on top of the other, in the greenhouse and the second bench is obviously light deprived. I'm considering putting in under bench lighting to raise our Sarracenia seedlings over the winter and would appreciate your thoughts on what lights would be good for this application.

Sincerely,

Phil Sheridan
Meadowview

[SundeWCitY]

honestly T5'ss are your best bet. they are high output and great spectrum and take up little space!

[meadowview]

Hi Viktorianeps:

My electrician mentioned T5's when I told him I was thinking of putting HPS and metal halide lights in the greenhouse. I think the T5's are a good suggestion for the under bench application where I have plenty of horizontal, but not vertical, room. I think I'll still go with HPS and metal halide in the ceiling of the greenhouse. I used cool white fluorescent bulbs as a kid and had excellent results with Sarracenia seedlings, provided the lights were close to the plants.

Thanks for your comments!

Sincerely,

Phil Sheridan

[rsivertsen]

Hey Phil, I think you'll find that some plants color up much nicer when you have some Gro-lux type bulbs mixed in with the full spectrum bulbs such as Sylvania's SunStick. Many plants do best with a blue shift in the spectrum, (even some UV) especially this time of year. The combination of cooler temps and the blue shift really brings out the deep reds in some plants including sphagnum. - Rich

[taz6122]

T5 for under the bench is an excellent choice. Initially a little expensive but well worth it for the output and power use. They are also space savers at 3/4" thick for the single bulb units. Double bulb units are thicker but not as deep. Power consumption for the single bulb is only 15w for a 21" and 21w for a 34". You may prefer to get the T5HO or the T5VHO. They are a little high for my shallow pockets though.