I got it at about 3 feet and I think it will be fine.Can't feel the heat with the back of my hand down by the soil.So I think it should be fine.I check on them all day so they'll be takin care of as far as watering enough,stretching, and air circulation.I know what I'm doing ,I've just never popped seedlings with a 1000w light,but thats all I have.Right now the weather is cold so the temp is about 70 with the light on in the room with no ciculation.
I turn the AC fan on for 10 minutes about 4 times a day to bring in fresh air from outside.I'd leave it on all the time if it was warmer outside.At night I keep the heater at 70.During the day I run the house fan for 10 minute 4 times a day.and constant fans running in the room for air movment.