10 Tips for Setting Up Air-Cooled Grow Lights

Looking to create a cooler garden that produces higher quality crops? Check out these ten time-honored tips for setting up air-cooled grow lights the right way, so you and your plants can enjoy maximum benefits!

Setting up clean, filtered, incoming air for your air-cooled grow lights

Short instructional video on setting up the incoming ventilation for air-cooled grow lights.

1. Blow, don't suck.

It is preferable to set up your air-cooled grow light reflectors so that the inline fan is positioned before the reflectors, blowing air through, rather than afterwards, sucking air. Multiple reasons: sucking hot, humid air through your fans will shorten their lifespan—and blowing air through your air-cooled grow light ventilation system creates a positive pressure inside it—meaning that any small leaks merely result in the air spilling out into your garden, to be dealt with by your garden's ventilation system. Sucking, on the other hand, creates a negative pressure which has the potential of bringing unfiltered air from your garden into your air-cooled grow light ventilation system. So remember—blow, don't suck!

Setting up an air-cooled grow light - the right way!

Great practical tips here!

2. Ventilate air-cooled hoods with air from outside your grow room

Use air from outside your garden, ideally from an adjacent room indoors. Using indoor air (rather than air from outside) means your garden's air-cooled grow lights are ventilated with air at a more stable temperature. If you live in a cold climate, using chilly or freezing air to cool your air-cooled reflectors may seem like a good thing to do, but over-cooling your lamps will actually impede their performance and alter the spectral distribution, especially in metal halide lamps. Cool, indoor air (around 60F - 70F) is ideal. There will still be around 6% PAR drop off but this is more than countered by the fact that you can safely position your grow lights closer to your plant canopy.

Does Air-Cooling Your Grow Lamp Reduce PAR Output / Light Intensity?

We use a PAR / Quantum meter to test PAR output with and without air-cooling.

4. Use insulated ducting—especially inside the growing space.

The whole point of air-cooled reflectors is to remove the excess heat generated from your HID high pressure sodium, metal halide, or dual spectrum lamps at source. Insulated ducting allows more of that heat to be channeled away, out of your grow room, without it simply leaking back through uninsulated ducting.

Insulated ducting coming from one of two air-input ports for my indoor garden.

5. Clean the glass on reflectors every week.

Even when using an intake filter, you'll still need to keep the glass on your reflectors super clean for optimal performance. Make it part of your weekly maintenance chore list. Obviously, only maintain your reflectors when the lights are off! Try popping in twenty minutes or so before lights-on for a quick spruce up!

Two air cooled reflectors, prior to the exit insulatated ducting being fitted

6. Use an infrared thermometer and PAR meter to bring lights closer to light-loving crops.

Air-cooled reflectors effectively open up new parts of the plant world for indoor gardeners—particularly species that enjoy high light conditions but at moderate temperatures — i.e. alpine crops from subtropical areas. In order to determine how much closer you can safely lower your air-cooled grow lights, get yourself an infrared thermometer and shine the beam at a leaf on your plant canopy directly beneath the grow light. If it reads more than 82F you should consider raising your lights a little. If less, you can probably lower them an inch or so at a time. Rememember, leafy green crops require less light than flowering and fruiting annuals. Aim towards 200 - 300 µmol for leafy greens and herbs and 500 - 700 µmol for plants like tomatoes, chillies and cucumbers.

7. Connect no more than two 6-inch reflectors or four 8-inch reflectors in series.

Obviously air heats up as it passes over HID lamps—that's the central principle of using air to ventilate and cool your grow lights! If ventilating your grow lights in series, don't go overboard or the last light in the row won't really receive any real cooling at all.

8. Keep ducting as straight as possible but remember to leave enough slack for raising lights up and down.

Bends and kinks in your ducting drastically reduce the efficiency of your inline fans. Try to keep ducting arranged as straight as possible, but remember that you will always need a little slack when adjusting the height of your grow lights.

Insulated ducting connecting two Magnum XXXL air-cooled reflectors by Sunlight Supply.

9. Keep your garden's ventilation and your air-cooled hoods' ventilation separate

Don't be tempted to simply take air from your indoor garden and use that to cool your air-cooled grow lights. You're kinda missing the point. By keeping your air-cooled reflectors' ventilation separate (i.e. bring air in separately to cool your lights) you can benefit from the cooling effect and be able to use supplemental carbon dioxide with less wastage. Also, garden air can be hot and humid—you don't want that blown over your lamps.

Insulated ducting set-up for air-cooled hoods.

The second part of our video on setting up the insulated ducting for air cooled reflectors.

10. Choose air-cooled reflectors from a reputable supplier with proper seals, quick-release catches and rust-proofing.

Unfortunately the popularity of air-cooled reflectors has led to some unscrupulous suppliers sourcing cheap knock-off imports. Personally, I swear by my Magnum XXXL air-cooled reflectors, manufacturered by Sunlight Supply in the United States. The build quality is excellent and the seals are very tight. I can't recommend them highly enough.