# Heat questions for 400w HPS



## Larnek (Jun 14, 2008)

I'm looking around at upgrading my current CFL grow for flowering. Hoping I will have 3-4 plants of Nirvana Citral in a portable standalone closet, 3ft x 2ft x 5ft. Looking between a HTG 400w HPS with built in ballast, a 400w external ballast or a 250w either/or. I am of course trying to do this as cheap as possible, don't expect any payback other than personal for my efforts and don't have any extra money to spend really. Growing soil with fox farms ocean and fox farms 3pack family of nutes. I'd like a cheap 400w w/ built in but I think it will make too much heat to dissapate with a just venting and strategically placed oscillating fans. Would the separate ballast work or should I just drop to 250w or will I even need more cooling there.. Ambient temp stays around 72F currently. Any help appreciated. Will also take cooling ideas from anyone. I've never used an HPS lamp so I just don't have a clue how much heat will be produced.


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## SkSMaN (Jun 16, 2008)

I would try the 400 with external ballast. With the Ballast outside your box it will help run a bit cooler. I think if you have good ventilation you should be OK for heat. I use a inline fan for vent, but you can usually get a good bathroom type for fairly low $$. Get the highest CFM you can afford (try for at least 150CFM if you can).


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## thc is good for me (Jun 27, 2008)

i have a 400 watt hps it will make your grow box about 15 deg hotter.  a 400 watt light will give you alot better results than cfls.


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## Melissa (Jun 27, 2008)

*you will need more extraction and fans upgrading from cfls 
i upgraded in my  grow and nearly killed them all by not giving enough ventaltion and fresh air eace:*


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## JohninWI (Jun 27, 2008)

I've been using a 400W HPS for about a month now, and the heat output has been pretty low.  I have it in a 2x4 foot by 6' tall cabinet that I built for a flower cabinet.  

In the "roof" of the cab, I installed a blower that goes to a carbon filter (yeah, that little space, even in very early flowering, gets REALLY dank--get a carbon filter!).  In the bottom of the back wall I installed a 3x10 vent that sucks in cool air.  I have an el cheapo 4" fan mounted to one wall.  About half of the stream blows on the plants, about half directly at the bulb.  Just enough air to gently make the plants sway is plenty.

The canopy stays around 76 degrees.  The soil about 70 degrees.  The only problem I can see with this setup is that I can't run CO2, since it's always being vented.

It's been working out great so far.  But I got greedy and first flowered at 1' tall.  Now I'm hoping I don't run out of vertical room!


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## PeaceKiller (Jun 27, 2008)

*thc* is right, a 400W HPS will raise the temp by 10-15 degress F. In that small a space, I wouldn't go with the contained unit, get the external ballast to keep out side the grow area as *sksman* suggests. Better safe than sorry.
Ventilation will also be needed. And if odor discretion is needed, a carbon filter that *JohninWI* suggests should absolutely be used. Even just 1 or 2 plants can really stink your whole place up something fierce.
The 400W HPS will provide you much better results than the CFL's, you'll thank yourself. Go with the 400W over the 250W, IMO.

Good luck Larnek


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## Capone (Jul 9, 2008)

good to know


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