Distance between plant and MH light?

[red_ss]

hey everyone.. could you please tell me what is the perfict distance bettwen the top of the plant and 400w MH ?

Thanks

 

[Stoney Bud]

hey everyone.. could you please tell me what is the perfict distance bettwen the top of the plant and 400w MH ?

Thanks

I've always used 18 inches between my 400 HPS and the plants. There really isn't any perfect distance. It depends on many other factors.

1. Is your light cooled with a ventilation tube?

2. Do you use fans in the grow area to extract the hot air?

3. Do you use other fans to move the air in the grow area?

4. How old and how large are the plants?

Try 18 inches and put a temperature gauge at plant top level. The heat at that level should be under 85 degrees F. If it's above that, move your light up. The light shouldn't feel "hot" to the back of your hand if you hold your hand at plant top level.

 

[red_ss]

thanks..yes ihave fans that keep the air moving.. but idont know if the light cooled with ven tube? the plants about 2 -3 weeks old and they are 3 iches tall

 

[Stoney Bud]

There are air cooled lights that have a tube attached to them for forced air to be pushed across the light bulb to cool it.

It makes a huge difference in the room temp.

 

[ito]

rolu of thumb if your hand can withstand the temp. you should be golden