1000 Watt DE HPS Air Cooling Effects

I have made a mistake. Been kicking around the idea of getting a new light, since pretty much right after buying the last two during black friday/cyber monday last year. True to my consumerist brainwashing, I decided that I should take advantage of the sales again this year. That makes sense. The mistake was buying something I hadn’t thoroughly researched first, which is rather uncharacteristic of me.

I bought a 1000 watt DE kit that came with MH and HPS bulbs, dimmable ballast, and air cooled hood. I’ve never looked into DE HPS beyond the headlines of better output, coverage, spectrum, and penetration. Having ran air cooled HPS plenty before, it seemed a no brainer to get an air cooled hood.

Off to the webz I went to learn more about my shiny new toy, only to find out that air cooling a DE HPS directly is bad. Quick look at the hood that I just ordered shows the bulb in the direct airflow. Attempted to contact customer service to change the order to a single end fixture, but it was too late. Oops.

I found a youtube vid with par measurements of a similar hood, and it dropped output by around 35% when air cooled at full fan speed. 35% is too much to lose.

I’m going to try to see just how slow I can run a fan through this hood to keep the top cool enough to mount close to the ceiling. I could take the glass off, and just run it open, but would rather try to cool it to get it closer to the ceiling.

Even with 35% losses, it will be a considerable addition to flowering lighting, and will allow me to grow much taller plants. After a couple cycles, it will likely get replaced by something much better. Maybe something like this when I get somewhere with higher ceilings:

Looks sweet for flexibility. It’s able to run MH, HPS, and CMH, with different reflectors available.

Anyhow, does anyone here have any solid info or experience with negative effects of directly air cooling a DE HPS? If I can’t get adequate cooling of the fixture with minimal airflow, I may just run it open, without the glass, and keep it further from the ceiling. Is that a bad idea to be avoided, or would it probably be alright?

Thanks for reading my book. Just doesn’t seem to be much discussion on the topic other than don’t do it unless you have a hood that doesn’t pass the air over the bulb.

Hoods dont dictate which bulb type it can run, only a ballast can decide that aspect.

You can run any cmh bulb in any hood. You need a cmh mogul socket adapter if using traditional cmh bulbs, or the new style cmh that uses traditional mogul socket threads.

I dont buy for a min that just because you air cool a bulb, you loose that much (35%) efficiency. The glass blocks a bit of usable spectrum. So, to combat that aspect, hit your local glass shop and have them cut you a new piece of glass. I swapped all 6 of mine out. Cost 100/per hood to do so


Get a vfd, and slow your air flow down. It will cool but now sub cool. They all have to be cooled bc they enjoy so much heat

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Scratching my fn head…

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I would run CMH… hands down easier to maintain heat, and better light spectrum.

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I meant emit so much heat. Fucking spell check.

When you have open hoods it doesn’t matter. When you have air cooled hoods it does matter. Typically there’s a opperating range where there’s less efficiency.

Staying right under that will ensure you get good bulb life and quality spectrum.


I’m into the new tech but I’m only running per watt lbs per light. If I don’t max out lbs per light I don’t Wana run that wattage.

I run de air cooled. But the air doesn’t flow over the bulb on mine, it in its own compartment. The bulb has to get hot enough to put out its correct spectrum or it loses efficiency a vdf will definitely help.


Your correct…direct air cooling on a DE bulb is not good, temperature is important. I didnt have to find this out first hand, I read about it proceeded accordingly. I used to run the AC/DE hoods with success when I had higher ceilings. Those DE bulbs run hot. How much AC are you running?


12k btu in summer have to turn them down to 750.

You don’t want to direct cool a de bulb you’ll burn it out prematurely and it will for sure lose efficiency. The bulb is engineered to burn in a way that the air around it must maintain X temperature. If it were me I would pull the glass and run it open or look for a diff solution if you have short cielings


I have been running 2x1000 cool tubes in veg. They have been running 24/7 pretty much for 3 years. Can’t say too much on efficiency but the bulbs seem to have no problem. But I run the sunsystem ac/de hoods in flower and from what I saw on there website video it was worth spending the extra Money to maintain output. My buddy at the shop thought I was crazy when I asked him to order them. He said he could get me a complete gavita fixture for the price of the hood alone but I’m happy plants are happy and room stays cool


I run these with the glass removed

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Can you post a picture of de’s in a cool tube?


I got 2 sun system acde hoods I’ll sell for 50% MSRP and I have two gavita ballasts also to go with them

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I’ll post when I get to the shop.

If you get a metal halide bulb too hot, it will explode in a most spectacular fashion. Hps bulbs pop internally when they blow and the outer glass remains intact. But halides will shower the room with flying glass that has a temperature similar to the surface of the sun.

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I’ve had 5-6 hps bulbs explode…

Pulling glass from shit is a nightmare


Interesting, I didn’t know hps could pop externally. I still have a plastic tool box with pieces of halide bulb melted into it.

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Depends on how old the bulb is… I’ve notoriously ran good and cheap bulbs far beyond their life span. Changing bulbs is like getting a hair cut for me…

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