Metal Halide light and seedlings - what power level?

I have 4 seedlings in a 4’x4’x6.5’ tent. The seedlings are 1/2" to 1" tall.
I have a 1000 watt Metal Halide bulb powered by a dimmable digital ballast that has 100%, 75% and 50% settings.
Right now I have the light 28 inches above the plants, set at 50% power.

I’m looking for opinions as to whether this is appropriate, or if I should increase the power level and/or the height.
Heat is definitely not an issue in this case - I can barely feel any heat below the air cooled reflector. But, I’m not sure if the seedlings should have more light or not.

A pic of the plants would help. It really depends on how they’re doing. If you see them stretching, then you’ll want to increase the lighting. If they’re burning, or curling, then decrease till you find the sweet spot.

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I agree with @raustin
Seedlings don’t need a lot of light since they don’t have many leaves yet so you can probably drop the power a bit but as she mentioned it depends on how the plants react to to amount of light :+1:


Okay, here are 3 photos. I should have said “three seedlings” earlier as the 4th one hasn’t popped up yet. After 4 days, which has me a little worried.

The last photo above is the one that is almost 2 inches tall.

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It actually looks like the leaves are turning down which means they may be getting too much light. I would decrease the lighting by dimming or raising the light.


Run it up to 32" and just watch for stretch

Done. Thanks, everyone!

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You’d be better off using cfls for seedlings. Less power consumption and less chance of frying them

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Thanks, I’ll keep that in mind. I’ll keep an eye on their health in case I need to go that route. They all got moved to 3 gallon pots so I can’t put them all back in my space bucket, but maybe I could hang the space bucket lid (which has five 32 watt 6500K CFL bulbs) over the plants.