How close should plants be to a 600w?experiencing some light bleaching

[bicycle racer]

i to switched from a 400 to a 600 and the leaves closest to the light are yellowed compared to lower foliage which is deep green i was 2 to 3 inches away heat is a non-issue. lol i had no idea i had to be 12 inches or more away.

 

[sedate]

I have a sealed, air-cooled 600 for my veg chamber - I keep it 10 inches away from the highest canopy.

Remember the "hand-test" - hold your hand at the top level of foilage and wait a few moments - if your hand is hot, your light is too close.

 

[justiceman]

Generally speaking from what I understand the rule of thumb is 12-18 inches. Sometimes even up to 24 inches if your system is hot. This all depends on how efficiently your cooling the hood or basically what the temps are directly underneath the lamp. I personally have a hygrometer. It measures the temp and humidity around the unit itself as well as having a wire that has a temp sensor on it so you can measure a different point of the room away from the unit itself. I position my wired temp sensor right above the middle of the canopy that way I know exactly what temp the canopy is at. That way I can judge whether I have to raise the light or not, but any where closer then 12 inches and it is possible that you might experience light bleaching or heat stress unless of course if the temps are really cool.

 

[MASSES 420KING]

that light bleaching is your lumens pouring down on your girls i keep my 600s anywhere between 8,10 inches the lowest and about 16 inches the farthest i have experienced the same issue but it turned out all good at end of harvest with a bumper crop

 

[burnalot420]

hey wassup guys, yea this problem was way back when, my lights are air cooled and don't get hot at all..after that crop i noticed that diff. strains could be like 5 inches away with no bleaching at all..they were even closed than those that experienced the bleaching..i like to keep em like 8-10 away from the air cooled 600's