Proper Lighting Distance

[ronvmpc]

I have a 400w HPS over 2 Clones that are about 10 inches tall now. My question is how far should i keep the light from the plants. Its in about 2'/3'/7' space. Any input would be awesome. If it helps I'm growing in 2 waterfarm pots.

 

[vonwolfen]

ronv
I am not an expert, but about 2-3 feet(1000watts I have are 4 feet from the tops. Some say thats a little to far but I am more concerned about heat which is one of my grow problems) from the tops. I assume you are in flowering since you are using a HPS..If the light is to close you will start to see burning on the leaves(sometimes yellowing which will turn to burns)...
If you are in veg then I have mine(400hps) at 4-5 feet from the tops

 

[bluetooth]

my 400 watt hps is about 15/18 inch from top of plant
or if ur useing a cool tube between 5/6 inch from top of plant
the easy way to solve your light issues is put ur hand under the light for a few seconds then if ur hand gets hot move it up a bit more
thats my 2c worth

 

[MASSES 420KING]

6-8 inches if flowering as long as you have an oscillating fan running your 400 uncooled can be dropped to 6-8 inches i keep my 600 hundreds 8-12 inches from my tops un vented wings

 

[bigdrty]

I keep my 1k lights about 10" from my tops by
Air cooling the Hoods....
but a good rule of thumb is, Just hold your hand over the tops and if your hand gets too hot just raise your hood until you get to your sweet spot. :sun2:

Drty.

 

[MASSES 420KING]

thats exactly how i do it

 

[l0g1c4l]

Hey ronv...i'd have to say conditions are different for everyone...but as a rule of thumb i've always heard that 18" is the safest distance...but really i've had some of my buds finish inches away from the bulb. Though, inches away is not recommended! Some strains like the heat more than others, so I would aim for somewhere in between 10" and 18"