Cool tube

A Cooltube reflector is used to prevent temperature problems in grow rooms. Especially in smaller room volumes with a large lighting setup, powerful NDL and MH lamps can quickly lead to heat problems. By connecting a Cooltube with a fan, the excess heat can be dissipated with the exhaust air, thus preventing the grow tent from heating up.

Structure of a Cool Tube

The interior and reflector are made of highly reflective aluminium, heat-resistant Duran or Pyrex glass. Depending on the manufacturer (Cooltubes are now marketed by many different brands), some have an additional reflective surface to protect the plants from heat, or offer the option of an internal slide-in fan. In terms of quality, the Cooltube reflector is available in different versions and price ranges.

Cheap replicas often have a colour problem in the glass after a while - clouding can occur, which reduces the light yield. The original, on the other hand, is by far one of the most popular special reflectors. Special because the Cooltube also works together with a normal grow reflector.

How does a Cooltube reflector work?

Calling a Cooltube a 'reflector' is actually not entirely correct, as it actually serves both exhaust air and reflection at the same time. The cool air, which is channelled through the Cooltube by a fan, reduces the temperature of the plant lamp inside the Cooltube. The hot air is then removed from the grow room. This also allows the light source to be brought closer to the plants, as there are no more waste heat problems - a correctly set up Cooltube can effectively remove 80% of the heat from high-pressure lamps up to 600 watts.

Cooltube for heat problems

The principle of this reflector is to dissipate heat from the growing room. The exhaust air is extracted directly through the Cooltube, or blown through if it is a tube fan fitted with plastic rotor blades.

The Cooltube has an opening on each side - so the air can be blown directly through it. The heat generated by the metal halide or sodium vapour lamp is immediately extracted and cannot escape into the growing space. This has the advantage that no further cooling is required, as the plants rarely tolerate temperatures above 30 degrees Celsius.

The attached reflector is better than an internal reflector, as it is easier to clean and the air can be blown through more easily without being obstructed by a reflector.

Connect Cooltube with fan

The Cooltube can be mounted vertically or horizontally. Where the fan is installed is an important decision, as it determines the direction of flow of the exhaust and supply air and therefore the ventilation mode. It is always advantageous to install the extraction fan in the exhaust air chain in front of the Cooltube, i.e. to blow cold air over the lamp instead of drawing hot air over the light source and the fan.

The following therefore applies to the Cooltube: only blow and never suck - when sucking, the hot air is drawn through the tube fan and can damage the blades due to the heat or expose the light source to unnecessary heat stress.

Cleaning the Cool Tube

Only use a soft cloth and glass leather for cleaning. Scratches on the glass greatly impair the luminosity - so be careful when cleaning.