How much Light for 4 foot tall setup?

[Ocelaris]

I'm making a new orchid tank, and I am trying to figure out how much light for vandas, as that will be my primary plant in this tank. I know 4 foot tall doesn't seem like that tall, but for an indoor tank with a 2 foot cabinet underneath, it's about as tall as is reasonable.

How much light is enough?

I have a plan of 2x 150w Metal halides putting out 12000 lumens each... I already have a 150w Metal halide, and a spare 100w MH, so was thinking I could just get another 150w setup, and reuse the 100w (which puts out ~9000 lumens initially). I'm trying to stay within/under that 500w boundary. maybe 2x150 + 1x100?

How bout it, anybody have any ideas? I want to stick with straight Metal halide, as I need as much penetration as possible... I'm not totally opposed to 2x 250 which put out 18,000 lumens each or roughly or a single 400w which is around 30,000 lumens.

I'll be sure to share when I pick stuff out.

Here's the bulb spec sheet I am looking at:

MHN-TD M81/E 150W/842 RX7s 1CT

it's a 4200k 85 CRI bulb, rated pretty highly by this comparison:

Aqua Botanic-light bulb comparison

Anyone with high lighting requirement plants want to share what quantity of light they have?

[Ross]

I'll just bet you are planning on lights at top of tank? Why not go with 48" t5 bank mounted vertically in front of tank? Just a thought. That will enable you to go with something more reasonable.

[Ocelaris]

Yeah, I have considered doing a T5 bank, but I'm trying to make it a show case sort of, and keep the front open (well, it will open for access; and the back I plan on having it mirrored, and/or hanging mounted plants...

I'm trying to imagine how to put T-5s in the back corner or something... Because trying to slam 500 watts of light through the top is a PITA... but since I want full sized Vandas, 4 feet is really even cutting it short... Maybe I could have light coming from below ? Would that throw off plant's natural inclination to grow towards the light if I had the lights below or to the side?

[Ross]

Originally Posted by Ocelaris

Would that throw off plant's natural inclination to grow towards the light if I had the lights below or to the side?

Interesting thought. Not sure what the answer to that would be. Maybe some others here might chime in?

[Ocelaris]

I've seen side lights done before on plants, and I believe it's pretty effective, but the wife's first instinct was ick! so... needs some more thinking through.

[Oldguypops]

Ocelaris,
I don't believe that putting the lights on the bottom would be a good idea.
I have read from several books that you aren't supposed to rotate your plants after they start to bloom because the change in the direction of light will make the flowers bloom sideways or even upside down. That is because the flower buds will generally point toward the source of light. (After they are all open, then they can be moved)

If their theory is correct, and unless you want all your flowers pointing down, I'd stick to the side or top for lights.

Just a thought.
Chris