How far for Mercury Halide ??

Okay, so I'm upgrading my grow room a bit and my veg used to be 7 - 4 foot flouro tubes.. just hung a 400 watt Mh over em and I realized a touch of leaf scald after about a day and a half just starting.. So how far should the light be placed above the plant tops? Just a note, tommorrow I am kicking that 400 up to a 1000 watt mh and moving the 400 to the flowers with a hps bulb.

Start with your lights as high as they go. Next, turn them on, let them get warmed up, and place your hand underneath the lights, palm down. As you move your hand from the top of your plants’ canopy up toward the light, you’ll feel a definite zone of cool space vs. hot space. Move your lights down to a point where you can keep your hand right above your plants and the back of it is cool. If you move your hand up just a bit, you’ll feel where it’s warm which is too hot for your plants.

It’s as simple as that! When it comes to the height of your plant grow lights, it’s as easy as using the back of your hand. If it’s too hot for you, it’s too hot for your plants.

It’s as simple as that! When it comes to the height of your plant grow lights, it’s as easy as using the back of your hand. If it’s too hot for you, it’s too hot for your plants

Lol.. "cool" pun intended thx ddowmed

Its not as easy as that actually, some plants can tolerate more heat than others.

A good basic rule 400= 12" 1000 = 18" When you find the perfect distance, hang a washer on a string to be able to move your lights up as the plants grow. My strong has a magnet on the other end that just attaches to my hood.

thx legally.. good idea i use chains os easy to mark