Marijuana -ReflectorsReflectors are essential to your indoor marijuana gardening success.
© Copyright, Nigel Salazar, 2015

Marijuana Grow Room Hydroponics Reflectors & Hoods Guide

Hydroponics nutrients innovator Michael Straumietis says hydroponics reflectors are a make or break item in your hydroponics cannabis grow rooms.

Straumietis, founder and owner of Advanced Nutrients, says inferior reflectors waste huge amount of light, and therefore electricity.

If possible, before you buy a specific reflector take a look at it when an HID bulb is installed and lit inside it, Straumietis advises.

What you’re looking for are “hot spots.”

These are places where the reflector creates especially bright areas that are accompanied by areas that aren’t getting full light (blind spots).

The best hydroponics reflectors don’t have hot spots or blind spots…. they evenly distribute light to your marijuana plants.

“I hope you go to a well-stocked hydroponics store and personally look at reflectors in operation,” Straumietis says. “That’s the best way to see how they’ll work in your grow room. Look for German aluminum on the interior, solid construction, and the right geometry so maximum light is reflected to your plants, with no waste. The more light that hits your plants’ leaves, the faster your growth, and the bigger your yields.”

Indoor marijuana growers know that hydroponics reflectors (sometimes called “hoods”) are an essential piece of cannabis grow room equipment.

Sure, a small percentage of cannabis growers use a bare-bulb approach, hanging bulbs without reflectors or hoods, usually in a “stadium” vertically-oriented plant set-up.

But most of us use reflectors on our bulbs because reflectors send light downwards towards marijuana plants rather than dispersing light up, down, and all around.

A secondary use of reflectors is to sequester bulb heat and keep that heat away from plants.

There are several types of marijuana grow room hydroponics reflectors & hoods, so let’s take a detailed look…

All reflectors are “air-cooled” because air moves around them and disperses heat, so it’s confusing that the hydroponics industry defines “air-cooled” as a reflector that has a tube or glassed-in chamber that isolates HID bulb heat.

Air is drawn from or through the tube or sealed hood and vented outside the grow room, thus removing bulb heat.

They also call this a “sealed” reflector because in some cases the tube is accompanied or replaced by a clear glass pane that plugs in to the bottom of the reflector to isolate heat.

Yet another confusing issue is that some sealed reflectors use water to transfer the heat out of the grow room, so you have a sealed, cooled, but not air-cooled reflector.

Water-cooled hydroponics reflectors are complicated and expensive to use, and only a small percentage of marijuana growers use them.

Air cooled reflectors have duct ports on each end. The type of ducting, how long it runs, the type of exhaust fan… all of these affect how well air-cooled reflectors remove heat from grow bulbs.

Air-cooled and water-cooled reflectors are useful in situations where you don’t want to use general marijuana grow room air conditioning to remove bulb heat.

But be aware that cooled/sealed reflectors have a glass tube or pane of glass between your HID bulb and your cannabis plants, and this decreases light intensity and light spectrum; in some cases your marijuana plants lose 5-15% of the total light and spectrum output.

So-called non-air cooled reflectors don’t have tubes, glass panes, or ports for ducts.

Bulb heat is dispersed throughout your marijuana grow room, including into the plant canopy.

To cool your room, you use overall grow room venting and/or air conditioning.

One problem with this is if you exhaust the heat from your general grow room and you’re also adding C02 to your marijuana grow room, you’re sucking out your added C02.

That’s one reason people use air-cooled sealed reflectors: bulb heat is removed, but added ambient C02 remains.

Both air-cooled and non-air cooled reflectors come in rectangular and box-like configurations which in general throw a square light profile common to the shape of most marijuana gardens.

Some non-air cooled reflectors are just a couple of metal “wings” that have no ends on them.

They’re lightweight and inexpensive, but 40% of the light goes onto the upper walls of the grow area, rather than down towards your marijuana plants.

The famous Adjust-a-Wing reflectors are an example of this open-ended reflector type.

Another type of non-air cooled reflector is distinguished by its shape: it’s parabolic.

The basically round shape of this reflector results in a wider light footprint, but this reflector also has more light loss when compared to the deeper versions of box-like hydroponics reflectors.

Yet another type of non-air cooled reflector is intended for double-ended (DE) hydroponics bulbs.

Double-ended bulbs shouldn’t be force-air cooled because it negatively affects their operation.

In most cases, the shape and depth of a DE reflector is similar to other non-air cooled reflectors.

Other differences in hydroponics reflectors include whether their internal surfaces are highly-reflective, dimpled aluminum, a mirror finish, or powder-coated white metal.

The aluminum and mirror-coated reflectors send more light to your marijuana plants, compared to the powder-coated interior reflectors.

Also, some reflectors give you the option of attaching the ballast directly to the reflector, rather than having a remote ballast.

The alleged benefit of an on-reflector ballast is to reduce radio frequency interference (RFI) created by remote ballasts.

On the other hand, reflectors attached to ballasts are often logistically inconvenient, and places ballast heat into the upper grow room along with bulb heat.

Most growers opt for interior aluminum or mirror because it offers 95% reflectivity, is long-lasting, and easy to clean.

Note also that some reflectors allow you to buy a replacement for the interior reflective material to replace a reflector interior that has been damaged by dust, spray, light, or other degradation.

Another important reflector/hood difference is size and shape. The hydroponics industry gives you small, medium, and large reflector choices.

As you’d expect, the smallest ones are for low-wattage HID bulbs such as 250-400 watts. These generally give you a 2 x 2 foot light footprint.

The mid-size reflectors are for 400-600 watt bulbs, although commercial marijuana growers sometimes use 1000-watt bulbs in mid-size reflectors to assure specific coverage. These reflectors give you up to 3 x 3 or 4 x 4 foot coverage.

Large size reflectors average about 30 inches in length, 24 inches in width, and 6-10 inches in depth.

Depending on whether you’re running a superior 1000-watt bulb and ballast or not, large hydroponics reflectors can give you up to 6 x 6 coverage, although a 5 x 5 or even a 4 x 4 profile (25 square feet or 16 square feet) is far more likely to give your marijuana plants full light intensity no matter where they are in the grow space. marijuana grow team members have used dozens of different brands and models of reflectors, and here are our favorites:

For fans of double-ended bulbs, the Panda-Double Ended reflector is an easy to assemble, lightweight, and comes in two sizes.

The Gavita Triplestar 600 reflector is a three-way adjustable mid-size reflector meant for bulbs that are 600-watt and lower-wattage bulbs.

The Hydrofarm Daystar reflector is a small, low-cost reflector that can be used for bulbs up to 1000-watt. It’s often used as a “greenhouse reflector” or to provide intense lighting in sea of green marijuana gardens. Note that the cordset for this reflector (and other makes and models of reflectors) often have to be ordered separately.

The Hydrofarm Radiant reflector is a mid-size hood that’s deeper than most other hydroponics reflectors and thus provides a more focused and intense light reflectivity footprint.

The Agrotech Magnum reflector comes in two sizes, and the large size is huge. Built entirely of galvanized steel and aluminum, the lightweight and very reflective Magnum reflectors are a popular choice for many growers.

The High Yield Big Daddy air-cooled reflector is probably the largest and most-versatile reflector you can find for your hydroponics marijuana grow room.

It measures 3 feet x 3 feet and has air-tight gasketed 8″ ports with  removable flanges so you can run your tube inline or straight up.

You can even use optional vent covers, and this reflector’s adjustable socket bracket allows you to customize your light footprint. Comes with a tempered glass lens. I recommend only using this reflector with a 1000-watt bulb.

If you don’t want or need a cooled reflector that puts extra glass between you and your plants, consider a “parabolic” reflector. Parabolic reflectors are somewhat round in shape, and have multiple reflecting surfaces that create a circular light footprint rather than a square one.

In some applications, they’re a better choice than rectangular or square reflectors. They tend to be best for larger marijuana gardens.

I like the Sun System Parabolic reflector. It can be run vertical or horizontal, and offers a reasonable reflectivity and light coverage.

For an innovative approach to air-cooling that helps eliminate light loss that often occurs with cooled reflectors, check out the Karma reflector.

I also suggest you visit, an online hydroponics retailer that has a big selection of reflectors and an online report that shows test results for reflector value and light efficiency.

Another resource that has a lot of different reflectors for you to look at is right here.

Definitely watch the hydroponics reflector educational videos embedded in this article.

One of them gives you a thorough tour of various hydroponics reflector types, brands, and models so you can consider what works best in your marijuana grow room.

Make every watt count!

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