hid lighting mh or hps

[lamellata]

Originally Posted by Pals

Hi,
I use mh and have no trouble flowering vandas, I use 250 watts which give out an average light measurement of 4,500 fc. Hps are supposed to be good for flowering but I wouldn't touch them, the light is very unnatural, makes the plants and flower colours look unnatural and is a very dingy light. My vandas flower 2-3 times a year so can't see what the fuss about sodium is?

Pals

good to hear this i am using a 400 watt mh and was contiplating a conversion bulb to get closer to the red spectrum but looks like i wont have to thanks for the info just what i was looking for

[s1214215]

Hi Everyone

How many footcandles/lumins might I expect to get from a metal halide unit say 100cm/40 inch from the bulb with a 6500k bulb (150 or 250 watt)? I am curious as I am still debating using T5 or MH for my orchidarium when I build it.

I plan an orchidarium that would be 90 or 100 cm from bulb to the tray bottom.

Brett

[kavanaru]

just my
in this thread you can see the light intensity I could measure at different distances from my two different T5 Sets:

http://www.orchidboard.com/community...-t5-lamps.html

they provide light for about 100 plants, and to be honest that's too much light... I have to add some filter for the mid-light plants (Cattleyas and Catasetinae are ok with it as it is, even though they are on the high side!)

T5 are not THAT expensive (at least not in Europe, therefore I expect them to be cehaper in USA) - OK, the lamp set was expensive in my case, as i bought some especial good looking set-ups

[jkhom]

I was looking at MH / HPS also. I read that the HPS give off an unnatural color although the spectrum is supposed to promote flowering and MH is supposed to promote for plant growth. Optimal set-up is supposed to be a combination of both, but that's a lot of power and heat.
I think the the MH bulbs are available with different spectrums and would be interested in knowing which one you are using.

[s1214215]

I am interested in this topic as I think both MH and T5 have merits. I am trying to assess what is best for my orchidarium to be built next year. I have yet to decide the height, but if it is T5, then it will be not taller than 80cm I think. If I go metal halide, then it may be taller if it means I can get more footcandles to the base of the orchidarium.

MH have a bit more strenght over distance - correct me if I am wrong here. They do however act more like spot lights that spread over distance, where T5 has greater/more even light spread overall.

From what I have read on various threads, it seems users of T5 are not using them on distances greater than 75cm or so from the bulbs. Where as I have seen MH users applying them to lengths of 1 metre or more.

I note the Grand Cayman Orchidarium is about 1 metre tall, but it uses power compacts that I think are a bit stronger than T5.

As to the colour spectrums available in MH, you can get anywhere from 5000K up to 25,000k bulbs from what I have seen.. You can get quite a range over the internet. Many Marine suppliers sell various bulbs. I am wondering about the Giesemann MEGACHROME Tropic DE 5,600K bulbs as it is designed for plant growth. Would that be around the light intensity needed on a MH bulb?

Brett

[Wendy]

My grow room is 8' x 8' and I use three HID bulbs...all 400 watts. One is HPS, one is MH and the other is a combination of both. Everything grows and flowers well and I don't mind the yellowish HPS light as long as it gets results.

[Magnus A]

I grow under both T5 straight tubes and MH. One advantage for T5 if the large "light area" that give a "soft" light so the plants does not shade itself or other as easy. If you use one MH it will in reality be a point sourceand the plants shade each other more.
I think it is much simplier to get uniform illumination with T5. But I will continue to use both (for different applications)

[Ross]

Sorry this topic always gets so "heated" but that's why all these technologies are so viable. Everyone finds what works for them. If hot lights are your thing, so be it. For me, I shed the higher electric bills and higher temps and went with t5. I cut a lot from my monthly bill and still grow everything from high-light Cats and Brassias and Laelias to even higher light lettuce and spinach and raddish under t5. You ought to see the lettuce leaves turn red with the really high light! A site to be seen. Never a leggy plant, never a bolted plant. To each his/her own I say.

[Royal]

Can I put a new MH bulb in the same fixture that currently has a HPS bulb?

[Wendy]

Originally Posted by RoyalOrchids

Can I put a new MH bulb in the same fixture that currently has a HPS bulb?

No. I don't know why but they have to be in the correct fixtures. MH in an MH fixture and HPS in an HPS fixture. There are bulbs that cover both spectrums and I believe they can be used in either but am not positive. I have one combo bulb and it came with the MH fixture....not sure if it would work in the HPS. Hopefully somebody else here can enlighten us on this topic.