600 watt metal halide distance

I have 2 clones in 1 gallons about 18 inches tall going under the mh to veg I want to keep them short I just topped and am transplanting into 5 gallons tonight how far should the light be for maximum development?

Got a Lux meter?
If not - put the back of your hand under the light & move it closer until it gets uncomfortably hot, then slowly move your hand away until it's a comfortable warm - that's the minimum distance.

Good luck

Leaf temp of about 27C.
IR guns are cheap on ebay.

osowhom said:

I have 2 clones in 1 gallons about 18 inches tall going under the mh to veg I want to keep them short I just topped and am transplanting into 5 gallons tonight how far should the light be for maximum development?

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I keep mine around 12” from the tops with a 400w

For 600w I would say 15”-24” depending upon your ability to control the temperature.

The back of your hand is as good a guide as any imo.

My climate isn't hot but when the sun is shining and it's say 20/25c a thermometer in direct sunlight can hit 30/40c+ so
I set an ambient temperature 25c and a radiated heat temperature back of my hand.

Star Dog said:

The back of your hand is as good a guide as any imo.

My climate isn't hot but when the sun is shining and it's say 20/25c a thermometer in direct sunlight can hit 30/40c+ so
I set an ambient temperature 25c and a radiated heat temperature back of my hand.

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Same, my fan speed controller is set to 23C and the sensor is out of direct light amongst the canopy.

jondamon said:

Same, my fan speed controller is set to 23C and the sensor is out of direct light amongst the canopy.

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Perfect set up imo, that's exactly what they're getting outside on a nice day.

I've got my temperature probe probe hanging at canopy height with a cardboard shade over it to guard against radiated heat.

I wonder how many people are actually measuring the radiated heat from their lights instead of the air temperature.

Star Dog said:

Perfect set up imo, that's exactly what they're getting outside on a nice day.

I've got my temperature probe probe hanging at canopy height with a cardboard shade over it to guard against radiated heat.

I wonder how many people are actually measuring the radiated heat from their lights instead of the air temperature.

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Probe is ringed.
It’s position doesn’t change.

Star Dog said:

I wonder how many people are actually measuring the radiated heat from their lights instead of the air temperature.

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too many to even bare thinking about lol.

This is about good I really was wanting to know how to keep them from stretching during veg but I guess using a net or lst I'm not now or ever supercropping

I've got a mh heat shield that might be worth a look if you want it closer.

When i did indoor grows i would hang a simple thermometer at canopy hieght and keep light where temp would average between 78-82'