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How far should I put my light?????


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#1
juanagrow?

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I have a 400w HPS, running a hydro setup. Don't even have sprouts yet. How far away from my baskets should I have my light hung. It's about 2 1/2 feet right now, but it seems a bit hot on the surface of my root tank. Should I have it higher? Any help would be appreciated.

#2
Bohbo

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#3
Doc6701

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16-18" if well ventilated will be perfect.

#4
soapman

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mine is aircooled and i leave my light like 2" from the tops of the plants. If your not venting your light, you'll have to determine the point at which you're most comfortable with for some that is 16-18" for others it could be closer just kinda depends on other things than just your light.

#5
juanagrow?

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2.5ft is pretty far for a 400W but for seedlings that should be fine. You need to give more detail nobody can really help you with that info. Do you have ventilation? Is your hood air cooled? Does it have Glass ? Etc Etc


Yes I do have ventilation, but my light is not air cooled. I'm running a 6in inline (250cfm) for my vent and a 4in inline (80cfm) for my intake. I also have a three area fans for circulation, 12in, 8in, 4in. I have the ducting from my vent running right to my light, so it pulls the air around the light . Should I not do this and just vent from the top of the grow area? My setup is inside a bathtub with panda film to enclose the area.

#6
Bohbo

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#7
Cyrate

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without spending money bro?

um take your 2 largest circ fans and point them directly at your bulb. if still not cool enough, i really doubt it will be enough. i would put that 250cfm on light duty. make it BLOW across the bulb. having it suck "near" the bulb does nothing without a tube. the 80cfm on exhaust and go for passive intake...or pc fan if need be.

Honestly, enclosing that light is going to be your best bet Bohbo said. check out mechs DIY cooltube for the cheap answer.

but to answer your original question a 400 watt HPS should be anywhere from 6"-21" depending on your canopy temps. With 12.5" be equiv to tropical sun at noon.
http://forum.grassci...tml#post2032731


i hope you get it sorted out.

#8
Doc6701

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mine is aircooled and i leave my light like 2" from the tops of the plants. If your not venting your light, you'll have to determine the point at which you're most comfortable with for some that is 16-18" for others it could be closer just kinda depends on other things than just your light.


Check your temperature gauge, make sure you are reading the outside temp.

I dont know anyone who can cool a HID enough to get it that close.

#9
Cyrate

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Check your temperature gauge, make sure you are reading the outside temp.

I dont know anyone who can cool a HID enough to get it that close.





and if you really do have your hid that close you are really shortening your lights 'footprint' and honestly running the risk of solarization and from what i hear,
"cooking" the flavanoids out of your flowers.

#10
Jaysew313

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Heres the chart for when they get a little bigger.

Attached Thumbnails

  • lighting_chart.jpg


#11
juanagrow?

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Well I've decided to take down the panda film and not enclose the area until I can get an aircooled hood. Reason being, I can control the temps a lot easier using the whole room because it's a bathroom and comes with a pre installed 120cfm vent :D lol.. Also the AC blows into the room bringing the temps down even more. With the panda film on I was getting 91degreesF temps with lights on and 82degreesF with lights off. Now I'm about 84degreesF on and 77degreesF off. Still not optimal but it will do until I can get an air cooled hood. I think I will just leave the tub open though and run ducting from the aircooled hood to the bathroom exaust fan so I can vent directly outside. Also what do you mean by checking the temperature gauges for outside temp?. Do you mean I should have them set to outdoors not indoors?

#12
Bohbo

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#13
juanagrow?

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Most thermostats that read inside and outside <$10-15 have a wired lead with a little coin type thing on end. That is the "outdoor" or remote sensor. So you put that sensor under your lights so you can see temp at canopy and then main unit on the top half of the room to get ambient room temp.



I see. I'm just using two gauges to do the same thing. One runs from the ceiling to the center of the "area" and the other will take the canopy temps. Heres a photo of the area and a link to my journal that I will be keeping for this grow. I need to get my camera up and running. I can't find my usb cord:confused:. Used the webcam for this one.

P.S. I've lowered the light after the picture.

My first grow..
http://forum.grassci...w-duo-grow.html

Attached Thumbnails

  • Picture 18.jpg


#14
ScreaminGreenie

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I've been looking for this chart--thanks Bro!

:hello:


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