Cooltube Glass Reflector – Air Cooled Hood for HPS & MH

The Cooltube Glass Reflector is the game-changer you need if you want to blast your plants with high-intensity light without turning your grow tent into an oven. This tubular, air-cooled reflector is designed to house High Pressure Sodium (HPS) or Metal Halide (MH) bulbs, allowing you to extract the heat generated by the lamp directly out of the room before it ever touches your canopy.

Is heat destroying your harvest potential?

Every indoor grower knows the struggle: you want to use a powerful 600W bulb to get those rock-hard buds, but the temperature in your Grow tents spikes uncontrollably. You end up raising the light so high to avoid burning the tips that the plants stretch and lose density.

It’s a frustrating cycle. High temperatures don't just stress your plants; they evaporate those precious terpenes you’ve worked so hard for, leaving you with hay-smelling weed. Plus, every inch you raise the light reduces the lumens your plants receive exponentially. You are literally paying for electricity that isn't converting into yield.

The Cooltube solves this instantly. By connecting this reflector to your Air Extraction System, you create a vacuum tunnel that sucks the hot air away from the bulb and vents it outside. The result? You can drop the light significantly closer to the plants—sometimes as close as 20-30 cm—doubling the light intensity without the heat stress.

Why the Cooltube improves your current setup

If you are currently using a standard open reflector (like a stucco or mirror finish wing), the heat from the bulb radiates downwards directly onto your plants. In summer or in small spaces, this is a recipe for disaster. The Cooltube changes the physics of your grow room. Instead of battling ambient heat, you are removing it at the source.

Compared to traditional reflectors, the Cooltube allows for a much more stable climate. It can lower the temperature at the canopy level by up to 4ºC. This stability means your plants can focus their energy on resin production rather than transpiration and survival. It’s the most cost-effective upgrade to professionalize your climate control.

Key features you’ll notice from the very first grow

• High-Resistance Glass: Made with special borosilicate glass that withstands extreme temperatures without cracking or reducing light spectrum transmission.
• Direct Heat Extraction: The tubular design connects seamlessly to ducting, allowing your extractor fan to pull hot air straight off the bulb.
• Closer Light Proximity: Because the glass remains cool to the touch (relative to a bare bulb), you can position the light much closer to the canopy for explosive growth.
• Versatile Compatibility: Adapted for 400W and 600W lamps, making it compatible with most standard Marijuana ballasts.
• Two Sizes Available: Choose between 125mm (5 inches) or 150mm (6 inches) diameters to match your existing ducting and extractor power.
• External Reflector Wings: Includes external wings to ensure light is directed downwards towards your crop, not wasted on the walls.

Who is this product especially interesting for?

The Cooltube is a mandatory tool for specific grower profiles. If you are growing in a closet, a small tent (like 80x80cm or 100x100cm), or living in a region with hot summers, this reflector is for you. It is also ideal for growers who want to maximize the Gram-per-Watt ratio by using the inverse square law of light—getting the bulb closer means significantly more energy hits the leaf surface.

How to integrate it into your routine without overcomplicating things

Setting up a Cooltube is easier than it looks. You simply replace your old reflector with this unit. Hang it using pulleys, screw in your HPS or MH bulb, and connect flexible aluminum ducting to one or both sides. Ideally, you want air to flow through the tube. Connect one end to a carbon filter (if scrubbing odors) and the other to your extractor fan. That’s it. You’ll see your thermometer drop within minutes of turning it on.

Frequently Asked Questions

Does the glass block UV light?

The glass used is high-quality and designed for horticulture. While all glass filters a tiny amount of UV, the gain in light intensity you get from moving the bulb closer far outweighs any minimal spectrum loss.

Can I use it with LED lights?

No, Cooltubes are specifically designed for High Intensity Discharge (HID) lamps like HPS and MH that generate significant heat. LEDs have their own cooling systems.

Do I need a separate extractor for the Cooltube?

You can incorporate it into your main extraction line (Filter > Cooltube > Extractor), but for maximum efficiency, some growers use a dedicated smaller fan just for the lights to keep the grow room exhaust separate.

What size should I choose, 125mm or 150mm?

This depends on your extractor fan and ducting. If you have a 600W bulb, the 150mm version is recommended as it allows for greater airflow and better cooling.

Personal Experience of Pevgrow’s CEO (Alan)

"I remember my first summer grow in a small apartment in Valencia. It was a disaster; my 600W HPS turned the closet into a sauna, and the buds ended up airy and loose. Switching to a Cooltube was the single best investment I made back then. It allowed me to keep growing high-grade HPS weed even in July without burning the crop. If you're struggling with heat, don't buy another fan—buy a Cooltube. It pays for itself in one harvest just by the increase in density you get from lowering the light."