movers are mechanical devices that, as the name implies, move an HID in
a fixed pattern over a garden. A light mover can increase the coverage
of a light by 140%. The real advantage is MUCH more light is available
to the plants when the light is in motion. With a stationary light all
that is shaded will remain in the shade, but with a mover the light
will hit from different angles giving better coverage.
Light movers are found in 2 configurations: spinning arms (kind of
like a ceiling fan) and along a rail that moves back and forth. The
rail version seems to be much more popular with Overgrowers, probably
because it will accommodate an air cooled fixture.
Light rails come in a variety of lengths, but most can be cut to
fit any application. Most growers prefer a "smart rail", that is, one
that pauses at each end of the rail for a period.
The biggest problem with air cooling a light on a mover seems to be
dealing with air duct slack. Apparently, if the light is close to the
tops of the plants, the duct may be dragged through the plants, thereby
damaging them. Overgrow poster Ferret devised a solution: Use a curtain
track, not a rod but the track that has all the little hangers inside
that slides very easily. I screwed this to the ceiling of room and used
light weight string to attach the air pipe to the little hangers in the
As the light moved the track hangers moved along with the air
pipe stopping the air ducting from dragging over your plant tops doing
The track cost about $15-$20 at any hardware or store. Simple to set up and it works .