Light distance question?

So im wondering how close other people run there lights to there plants. Im new to inddor growing and vegging some ladies out inddors for this years outdoor op.
I have a 600w MH light, in a "euro" hood, with 6in ports, im running stiff aluminum ducting from the light out the tent and from a 440CFM fan into the light.
View attachment 2127946
Heres a pic of what i have going on.
My question is how close does everyone else run there 600's/whats a good rule of thumb for the best light penetration?
Its warm for about the first 4-5 inches under the light, not hot, and after that you cant feel heat from it really if that helps.....

8" is about as close as you want or need to get as long as you can control the temps on your plants. Good luck.

at the stage of the game your in right now you could raise that thing to the top of the tent and be fine, but in a couple weeks i would go with what philip said 8 inch maybe more maybe less, as they get bigger can get closer. got buds touching the glass of my aircooled hood for past 2 weeks....

nice setup BTW seems like alot of plants for that tent though. if they are feminized might want to consider 12/12 from seed or they may get pretty big in there.

Didn't notice the plants. Matt is right about that...you will have to run some short veg times to fit them all in there unless that is just your veg tent.

Also, what's up with the fan? Looks like it is pulling air from outside through the light and exhausting it into the tent? Is that right? If so you need to change that. If you are using air from the tent and pushing it through the lights then that needs to change as well.

Drop a thermometer at canopy height and keep the temps in the mid 70's if you can. I have a few of the el cheapo wal mart indoor outdoor hi/lo thermometers that have a remote on a wire lead. I drop the probe down to canopy level and monitor this way. IMHO you are better off with your lights at 18-20" away with a good spread and temps than you are 8" away, small sweet spot and hard to control temps.

High heat = fluffy buds. No density = low weight.

I'm not disputing the others, every setup is different and unique and you have to find the balance that works within your system. but that's the key, balance. You have one light fixture there, find the height that gives you optimum spread for uniform growth and the most managable tempuratures.

RetiredMatthebrute said:

nice setup BTW seems like alot of plants for that tent though. if they are feminized might want to consider 12/12 from seed or they may get pretty big in there.

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This is my veg tent for my 2012 outdoor grow they are going to veg in here untill they are 18-24inches tall and then be takin to there summer homes!

phillipchristian said:

Also, what's up with the fan? Looks like it is pulling air from outside through the light and exhausting it into the tent? Is that right? If so you need to change that. If you are using air from the tent and pushing it through the lights then that needs to change as well.

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Why would i pull air in from outside, through my light, out my fan and into my tent. Thats RETARDED! Id be filling my tent with hot air!
And how is suicking air in from my tent, through my light and out wrong? It sucks fresh air in through my passive air vents in the bottom of my tent and brings in fresh air, at the same time as clearing the hot air from my light.. im confused with your statement please elaborate???????

budleydoright said:

Drop a thermometer at canopy height and keep the temps in the mid 70's if you can. I have a few of the el cheapo wal mart indoor outdoor hi/lo thermometers that have a remote on a wire lead. I drop the probe down to canopy level and monitor this way. IMHO you are better off with your lights at 18-20" away with a good spread and temps than you are 8" away, small sweet spot and hard to control temps.

High heat = fluffy buds. No density = low weight.

I'm not disputing the others, every setup is different and unique and you have to find the balance that works within your system. but that's the key, balance. You have one light fixture there, find the height that gives you optimum spread for uniform growth and the most managable tempuratures.

Click to expand...

If you look at the picture i have exactally one of these thermometers in my tent, its hanging from a string and is about 12" above my light, i try and maintain a temp of 75 f, but its been hard with new england weather being what it is this spring, so im happy as long as it stays between 65-90ish for now they are outdoor plants and will be seeing these conditions all summer anyways.

Thank you though guys, from what im understanding 8"-16" is prime if i can maintain overall tent temps near 75ish correct?

Also anyone have a picture of light burn so i know to watch out for?

I think he is just proud of the setup and took it wrongly as an attack. Probably thought that was the last thing he'd get a comment about. Let's show him we can turn the other cheek the first time.

We're here to help ya man, that's what you asked for. Just be nice to us lol.

Your question is about light distancing, so I'll answer that first. As long as you can keep it under 75, I'm able to keep my plants 10-12" away from the glass with 600watts as long as I have a wall mounted or clip fan blowing under the reflector lightly. However, I think growing that close to the light in veg may also cause them to stretch, but I'm not 100% on that.

Now back to your tent...as soon as possible put a table or something under that laundry basket to prop the plants up a couple feet. Then raise the reflector up a couple feet as well, and take off a couple feet of ducting. That's also not the preferred kind of ducting you wanna use, I made the same mistake starting out. You wanna get the flexible kind, they sell it at grow stores or home depot too.

Here, I copied this from another site instead of explaining it. This should help you.

No need to keep a 600 watt any closer than 20-24 inches from the canopy....

phillipchristian said:

Didn't notice the plants. Matt is right about that...you will have to run some short veg times to fit them all in there unless that is just your veg tent.

Also, what's up with the fan? Looks like it is pulling air from outside through the light and exhausting it into the tent? Is that right? If so you need to change that. If you are using air from the tent and pushing it through the lights then that needs to change as well.

Click to expand...

Obviously the fan is drawing air from the tent, pushing it through the light and out of then exhausting it out of the tent. Nothing wrong with that set up at all........
Guess your 10 yrs of experience and 1200 watt imagination is not all that observant.......

Sorry, I got high and forgot to paste it after I copied it, glad I checked back haha.

There are many methods to cooling HID lights. Here are a few:

Type 1 - Inline Series (without CO2)

There are many variations of this type of setup. In this setup, the system used to air cool the lights is also used to ventilate and clean the air being exhausted from the grow room. This system effectively uses one fan to do the job of two fans. The fan will need to be sized larger than what is required to just ventilate the room. The fan will need to pull air through a carbon filter, through one or more lights and exhaust the hot air. This system is suited for small to medium growing areas without the use of CO2. The fan should be running continuously during the light period (which means it is possible to plug the fan into the same timer that is used to operate the lights [provided they both don't exceed the amperage rating of the timer]). Ideally, the fan should stay on a little longer, since it takes a while for the bulb, reflector, ducting, etc. to cool down completely (which means you would have to use a second timer).

Materials required:

• Air Cooled Reflectors
• Ducting to match reflector and fan - 4", 6", 8"
• Duct Clamps - 4", 6", 8"
• Centrifugal Fan
• Carbon Filter
• Timer for Fan
• Grow Yoyos

Type 2 - Inline Series (with CO2)

This type of cooling system pulls air (preferably from a cool air source) through the lights and exhausts it outside or into another area. The air passing through the light never comes in contact with CO2-rich air in the grow room. This allows the grower to control CO2, temperature, humidity and also groom ventilation. This also allows the grower to create a sealed environment. This type of setup is suited to small to medium sized areas. If 2 x 400w lights are being used in a grow room, then a 4" or 6" fan could be used to cool the lights. If the air that is being used to cool the lights is warm/hot, then a 6" fan should be used; if the air is cool then a 4" fan can be used. Use 6" ducting to connect the fan to the reflectors. With the addition of a 6" ZoneMaster Motorized Damper on the intake side, you will get the added benefit of keeping moisture and dust from entering the system at night, which could cause condensation and alter the temperature and humidity levels in the grow room as well. The Zone Control Damper should be plugged into the same timer as the fan. When the lights turn on and the fan is activated to cool the lights, the Zone Control Damper is also activated, thus allowing cooler intake air to cool the lighting system. Alternatively, you could install a 6" Suncourt inline booster fan on the intake side in place of the damper. When the lights turn on and the fan is activated to cool the lights the booster fan is also activated, creating positive pressure in the air cooling system and increasing the air flow and efficiency of the system. This is especially useful if you decide to add another light in the future or you find that the single fan system isn't moving enough air (which is a common problem when you use too much ducting or too many sharp bends in the duct run).


Materials required:

• Air Cooled Reflectors
• Ducting to match reflector and fan - 4", 6", 8"
• Duct Clamps - 4", 6", 8"
• Centrifugal Fan
• ZoneMaster Motorized Damper
• Suncourt Fan
• Timer for Fan
• Grow Yoyos

Type 3 - Parallel Series (Without CO2)

This type of system is similar to Type 1 above, however this configuration is more suitable for larger growing areas. This system utilizes only one fan to cool numerous lights. It is more efficient to cool lights this way instead of using one fan to pull air through numerous reflectors in one line. It's not efficient to pull hot air from one reflector into another (which is also producing heat) into another (even more heat) and into another (yet more heat). This will cause too much heat to radiate from the hot reflectors into the grow room. It also puts a tremendous strain on the fan when you go from a 10" or 12" fan into a long run of 4" or 6" ducting. This strain will shorten the life of the fan and use more energy. By using "Y" Adapters you can can go from a 10" or 12" fan into two 6" or 8" runs - a much more efficient solution to the problem. You can either leave the intake ends on the last two reflectors open, or (as illustrated below) you can add another "Y" Adapter, ducting and a carbon filter to clean the air before it comes in contact with the system. Not only does this prevent any odor from exiting the room, it also keeps dust from entering the lighting system, which could accumulate on the glass lens and reduce the amount of light available to the plants.

Materials required:

• Air Cooled Reflectors
• Ducting to match reflector and fan - 4", 6", 8"
• Y Adapters - various sizes
• Duct Clamps - 4", 6", 8"
• Centrifugal Fan
• Carbon Filter
• Timer for Fan
• Grow Yoyos

Type 4 - Parallel Series (With CO2)

This is by far the most popular setup for air cooled lights that are utilizing supplemental CO2 in the growing area. As with the Type 2 system above, air is pulled from another area to cool the lights. With the inclusion of a "Y" adapter the grower can air cool numerous lights with only one fan. If 4 x 1000w lights are being used in a grow room then an 8" or larger fan should be used to cool the lights. Use an 8" x 6" x 6" "Y" Adapter to run from the fan to the reflectors. BGH offers several different sizes of "Y" Adapters and Duct Reducers allowing you to use just about any size fan with any size ducting. The same setup can be used on the intake side with the addition of an 8" ZoneMaster Motorized Damper or 8" Suncourt Inline Booster Fan (as explained in Type 2, above). The Zone Control or Suncourt fan should be plugged in with the same timer as the fan. When the lights turn on and the fan is activated to cool the lights, the Zone Control or booster fan is also activated, thus allowing cooler intake air to cool the lighting system.

Materials required:

• Air Cooled Reflectors
• Ducting to match reflector and fan - 4", 6", 8"
• Y Adapters - various sizes
• Duct Clamps - 4", 6", 8"
• Fan
• Carbon Filter
• ZoneMaster Motorized Damper
• Timer for Fan
• Grow Yoyos

Alexander Supertramp said:

Obviously the fan is drawing air from the tent, pushing it through the light and out of then exhausting it out of the tent. Nothing wrong with that set up at all........
Guess your 10 yrs of experience and 1200 watt imagination is not all that observant.......

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Your imagination is apparently the one that needs work buddy. Check out the graph above and you'll understand why it's important to draw air through the reflector and not just blow air at it instead. There's a really big difference.

Did you make that comment just to try to start shit again on this thread? Keep it positive man. Lmao.

With his simple set up with no carbon filter or CO2 enrichment pulling or pushing the air will accomplish the very same thing. Only difference would be if the hood has a few leaks then a bit of air may leak from it when being pushed, nothing duct tape wont take care of.....again his set up is just fine......

Alexander Supertramp said:

With his simple set up with no carbon filter or CO2 enrichment pulling or pushing the air will accomplish the very same thing. Only difference would be if the hood has a few leaks then a bit of air may leak from it when being pushed, nothing duct tape wont take care of.....again his set up is just fine......

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LMAO! You got it right Witch...he's only here to start shit. I guess he's never used and inline fan before so therefore he's never grown before. Maybe he doesn't understand how motors and gears work either cause he sure as hell doesn't understand putting positive pressure in front of a fan will shorten it's life span and wear out it's motor. Just let him ramble on like a jackass. The more he talks the smarter he makes all of us look.

So I guess hose behind a fan pulling does not cause a negative pressure? Making the fan work equally as hard trying to pull the same volume of air as it would be trying to push through the same size circuit....yep yep yep same same with negliable difference....maybe they are called inline fans because you can mount them in the line anywhere you please........

Alexander Supertramp said:

Vortex Powerfans are high performance inline duct blowers constructed from quality steel with heavy duty attractive hammertone powdered coat finish. The extended collar allows for easy duct installation and taping. Superior quality and smart design ensure vibration-free operation with balanced motorized impellers with permanently lubricated ball bearings. Include 6' power cords, and galvanized mounting brackets allowing both horizontal and vertical installation.

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Just keeps making me look smarter. Keep going buddy. Ignorance is bliss.

Axial fans perform equally well pulling or pushing air. Its what they are designed to do, bottom line.....stoner logic does not apply.........

LMAO! I guess physics wasn't a requirement at ITT Tech?