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Question for HPS / Metal Halide Experts

C

cmpman1974

For those of you who have used these lighting fixtures, I'm looking for advice. I have a 400 watt Hydrofarm Convertible HPS/MH integrated ballast/light unit. My understanding is these should be placed 2-3' above plants to avoid burning of leaves. I want to know if used in an open basement with ambient temps around 65 degrees, would these overheat w/o additional cooling precautions. Are they safe w/o hooking up exhaust fans/tubing.

I picked one up for a nice price last season and wanted to try it. People like Pepper Ridge Farm showed some spectacular results with a 400 watt Metal Halide when used for 1-2 months before plant-out. It would not be my 'full-time' light as I'm not interested in growing to maturity (fruiting). I may at some point, but for me chiles indoor just don't yield enough to compensate for electrical expense.

Any pictures/ideas are appreciated. Also, would an oscillating fan do the job? I asked a local hydro store, but can't say I was too satisfied with the preciseness of their response. Go figure. lol.

Chris
 
cmpman1974 said:
For those of you who have used these lighting fixtures, I'm looking for advice. I have a 400 watt Hydrofarm Convertible HPS/MH integrated ballast/light unit. My understanding is these should be placed 2-3' above plants to avoid burning of leaves. I want to know if used in an open basement with ambient temps around 65 degrees, would these overheat w/o additional cooling precautions. Are they safe w/o hooking up exhaust fans/tubing.

I picked one up for a nice price last season and wanted to try it. People like Pepper Ridge Farm showed some spectacular results with a 400 watt Metal Halide when used for 1-2 months before plant-out. It would not be my 'full-time' light as I'm not interested in growing to maturity (fruiting). I may at some point, but for me chiles indoor just don't yield enough to compensate for electrical expense.

Any pictures/ideas are appreciated. Also, would an oscillating fan do the job? I asked a local hydro store, but can't say I was too satisfied with the preciseness of their response. Go figure. lol.

Chris
Click to expand...

You need to be asking about the ballast. Find out if it's a magnetic or digital air cooled ballast. If it's only a 400w I wouldnt be to concerned with over heating. Provided the ballast is of decent quality. Hope this helps. I'm not an expert but I know a decent amount
 
This is the unit:

http://homeharvest.com/SunburstCompactConvertible.htm

It says it is the coolest running of all lights, but that is just a statement. It doesn't mean it still wouldn't put out a lot of heat. It doesn't say if it's digital or not or maybe I'm just not reading it right?

Chris
 
cmpman1974 said:
This is the unit:

http://homeharvest.c...Convertible.htm

It says it is the coolest running of all lights, but that is just a statement. It doesn't mean it still wouldn't put out a lot of heat. It doesn't say if it's digital or not or maybe I'm just not reading it right?

Chris
Click to expand...

I didnt see anything in there about a ballast at all? You might want to call them about it! Heres the one I'm getting, I calles the guy at the store hes nice and said he'd even give me the better digital ballast so the light can be dimmable! http://www.ebay.com/itm/NEW-600-WATT-HPS-GROW-LIGHT-SYSTEM-600W-6-REFLECTOR-HOOD-SUN-120V-240V-W-BULB-/220912124210?pt=LH_DefaultDomain_0&hash=item336f638132
 
A 400w bulb will throught out some heat but you need to take into account room size(volume) then you can work out roughly how much ventilation you need. As to keeping it 2-3 foot away that would only be for newly popped seedlings. A full grown chilli can get as close as 8 inches but don't take this a set numbers as its varies strain to strain and plant to plant. but for starters I'd put it a foot away once they're well established. go with the MH if you only want to veg with them as they're rich in blue spectrum. But they do throw out more heat as opposed to a HPS.
 
Chris,

I am running a 600w dimmible MH/HPS right now and my grow aint going so well. The bright side is it has taught me some things not to do. So, keep in mind our growing conditions are a bit different but here is how it runs in my setup.

I have a 5x5x7 tent and the light is hung at the highest point away from my plants. When running at full power (600w) and no other factors I get temp gains as much as 30 degrees. Add an oscillating fan in there and I get temps to drop anywhere from 5-10 degrees, and turn on the vent (160 cfm) and Im down another 10 or so. So for an example I have had temps in my tent at 100 degrees when it is 75 in my garage before I turned on the fans and stuff. The ballast is not air cooled so you should not have this extreme. When I run it at 75% (450w) I am usually pretty steady at about 20 degrees higher than ambient and I run my fan on low to get me a couple degree drop to keep my temps at around 75-85 degrees.

Depending on your space and airflow you could probably see gains in the neighborhood of 10-20 degrees without anything to combat that. Throw a fan in there and you should be able to displace the heat and create a more consistent environment.

I don't know about mature plants, but in my experience 3 feet away was too close for seedlings. They fried as soon as they popped up. I would start at about 3 or so feet for established plants and THEN move it closer.
 
Chris if you do not mind sharing, what did you pay for the light. I have a chance to get one for 150 bucks. Just comparing
 
I am using a 1000w HPS in an open area with about the same ambient temp. It really depends on the size of the room, but with mine I only see about 3-4 degrees difference with the light on. I would definitely recommend an oscillating fan for a number of reasons, but it will get very hot directly under the light if you do not disperse the heat somehow.
 
I think you are asking if the reflector hood would overheat? Maybe pop out the lens and let it run a bit. Mine is a cheap reflector that is open so no worries here. Maybe poping the lense out if you can will let it breath. Just use caution and don't get the bulb wet.I think the venting is for enclosed tents. I am more than likely wrong though.
 
It really depends upon the heat loss of your basement and ambient weather conditions.
Worst it (luminaire) will produce is about 1000 btu/hr.
 
I agree with theghostpepperstore and MGOLD and oscillating fan should work fine, I dont think I'd recommend starting out with a 400w MH. But if you do I'd put it at the top of your tent and the seedlings on the very bottom of the tent. Prodigal the venting is for the zippable tents and I believe they can be attatched to an enclosed hooded MH/HPS light. If you click on my ebay link above you will see the hood I want is the same as smpman and that there is a large hole in the hood that should I believe allow for an air ducting fan vent
 
I ran 400 watt MH/HPS and had no problems in a small room with a cool tube and get my light as close as 12" with NO heat on the plants at all. However when I went up to 1000 watt HPS I picked up a cheap 4" duct fan for around $16 from HD. Doesn't look like much, but it's rated at 65cfm.

The key was the design of the cool tube. Since it's pretty much a straight line light even a small fan close to the entrance of the light is going to make a huge difference. However if you spend $20 for a cheap duct fan, some ducting and duct tape it will move almost all the heat off your grow area. You still have to keep in mind where your putting the heat. For me in the garage was fine since it was always pretty cold anyway.

Inexpensive duct fan
7f44b6b1-98db-4165-99f2-802ef3be9e43_300.jpg


Cool Tube

Cooltube_Reflector_120mm_x_400mm__16719_zoom.jpg
 
400 watt HID light in an open area with ambient temp of 65 shouldnt be a problem. No need for ventillating the hot air, just try to get fresh air to come in every now and then.
 
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