1000w light distance

No glass on my magnum xxxl hoods. I am being told many different things. I've read on here that plants get up to 8 inches from the glass and do fine. of course that guy is using the glass and probably has proper AC. I have a badass AC. Most people say to keep it about 1 1/2 feet away. Last night, a guy told me to keep them 4-5 feet away. I look at pics from the professional warehouses online, and some of them show their lights way high above the canopy. I am so confused.

Atleast a foot to 18 inches

Use the back of your habd to guage heat hold it at a certain distance from light if its too hot for ur hand its too hot for plants

Right. I just keep seeing big grows with lights that are over 4 feet above the canopy, and it's puzzling.

Depending on the light it can bleach the buds

Check the temp at canopy level. That's best way to see for your room. With no glass id say minimum 16 inches.. Closer to 24 is best . When I say minimum I don't mean it will grow best at this I say that like if your nugs finish 16 inches from bulb with decent airflow you shouldn't get light bleaching

Jumfrey13 said:

Right. I just keep seeing big grows with lights that are over 4 feet above the canopy, and it's puzzling.

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Most pros keep their lights several feet above the plants, that's pretty common

lawlrus said:

Most pros keep their lights several feet above the plants, that's pretty common

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How many feet is several? And what defines pro in the cannabis industry. Just curious because I find your statement to be false

patrickkawi37 said:

How many feet is several? And what defines pro in the cannabis industry. Just curious because I find your statement to be false

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2 feet for sure with no glass, Id start at 3 feet and work my way down from there. Professional usually means: occupation as mean of livelihood or gain.

Wow i wouldnt attempt to take a 1kw xxl without a glass any closer then 24"

a mongo frog said:

2 feet for sure with no glass, Id start at 3 feet and work my way down from there. Professional usually means: occupation as mean of livelihood or gain.

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Mine are at 30 inches right now with small signs of heat stress couple days into flower .. "Occupation as 'means of livelihood or gain" I like that . So im a pro then . I feel good now

A lot of the PAR readings I have seen on 1000 watt bulbs seem to suggest that 2 feet is best, if you can maintain the temps... even without glass you can exhaust those hoods which helps.

If people want to be technical its a loaded question. A pro would calculate lights over area and distance to get a certain ppfd at a certain height. They'd be accounting for wall reflectivity, and reflector design to get the correct overlap.

Well if your a real pro, you wouldn't even do that, you'd be hiring a specialized contractor to set everything up. Of course this wouldn't be some small time grow.

But anyways...........

There's lots of dumb people out there. If the light is close and its really warm on your hand at plant height, its too close. If the plant starts bleaching its too close.
If its so far away that light is spread on the ground where there are no plants, its either too far, or you're not growing enough plants

- Jiji

OK thank you.

I have no experience without glass. Canopy is 12" from the bulb, which is about two inches from the glass, so my plants are only about 10" from glass. I am growing Chernobyl and Jillybean by TGA along with a friends strain under a 1k Eyehortilux Super HPS with an air cooled XXL hood in a 4x4 tent. These are finishing week five of flowering, bulb has been this close since stretch stopped, light tolerance is very strain dependent though as well. Personally, I have never had a light more than 18" from canopy.

Urbz said:

I have no experience without glass. Canopy is 12" from the bulb, which is about two inches from the glass, so my plants are only about 10" from glass. I am growing Chernobyl and Jillybean by TGA along with a friends strain under a 1k Eyehortilux Super HPS with an air cooled XXL hood in a 4x4 tent. These are finishing week five of flowering, bulb has been this close since stretch stopped, light tolerance is very strain dependent though as well. Personally, I have never had a light more than 18" from canopy.

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Lovely

With open bulb MH, less than 18" seems to cook them. I keep a graduated 24" stick handy for checking things. So, MH I keep around 20" and HPS around 18". My cool white T5s in my cloning cabinet can be within a couple inches...let them grow into the light and it too will bleach. Last grow I augmented my HPS with T5 blues and while I think I could have gone closer I kept it at the HPS height.

Yes I agree with bravedave

Jumfrey13 said:

OK thank you.

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Consider one of these -



Place the "outdoor temp" lead at the warmest part of your canopy and the body of the thermometer a few feet away and adjust accordingly. Of course a fan etc. is part of the equation.

patrickkawi37 said:

Mine are at 30 inches right now with small signs of heat stress couple days into flower .. "Occupation as 'means of livelihood or gain" I like that . So im a pro then . I feel good now

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I deff got light burn and slight bleaching on my h-scrog under two 1000k w se ac hps. That was at 24inches, now at 32in .

I'm going into wk 7; is this reversible or have I already done quite a bit of damage to quality of end product? Under the other flower room 2 and 3 v-scrog cmh's and QB's doing great.

Harder to keep Temps down now due to increasing outside Temps. U can see from pic bleaching and leaf clawing/curling. Temps are 74 to 78 F lights ON, 67F to 72 F lights off,, RH 47% to 53 %Gelato41.