and finaly.
in initial purchase price, HPS systems are the most expensive of all lighting units. MH lamps are a little cheaper, and fluorescents the cheapest of all. However, this takes into account only the initial outlay. If we calculate the cost per unit of light produced, the positions are reversed; HPS lamps become the cheapest, followed by MH lamps. The fluorescents become much more expensive.

LIGHTING ACCESSORIES

Outdoors, plants receive light from many directions. Over the course of the day, the sun bathes plants in light starting in the east and travelling west. Leaves shaded during part of the day are under full sun at other times. When there is some cloud cover, the light is dispersed, so leaves are more evenly bathed in light.
Indoors, using a single stationary light, some plant parts are always shaded while others are always lit. With a light in the centre of the garden, plants closer to the source receive brighter light than those at the periphery.

LIGHT MOVERS

Light movers were invented to solve light distribution problems. The mover carries the lamp over a fixed course so that the entire garden comes directly under the light part of the time. Some movers shuttle the lamps quickly, so, that the light passes over the garden in less than a minute. Other movers take more time to traverse the course. Both types improve light distribution in the garden. As a result, the plants grow at an even rate. The plants do not stretch the way they do under a stationary light. Instead, they grow straighter, with more symmetry.
The rotating units are most effective in block-shaped areas, while the shuttles, which go back and forth, are most effective in rectangular spaces.

REFLECTIVE MATERIAL

Electrically generated light is expensive, so any that is generated should be conserved. Efficient indoor gardens use reflective material to shoot back light thatstrays out of the perimeter. Growers cover walls with white flat paint, aluminum foil or metallic gift wrap, maylar, white polyethylene plastic, or styrofoam.
Flat white paint diffracts the light so that it is distributed more evenly throughout the garden. Some greenhouse whits paint is formulated with titanium for maximum reflectivity.
Aluminum foil is very reflective and inexpensive. The best way to use it is to line walls and surfaces with it, rather than to leave it hanging. The heavy-duty 18-inch width is very convenient. Use the dull side, since it diffracts the light. Metallic wrapping paper is very reflective, inexpensive, and easier to use than aluminum foil. It comes in 26-inch to 30-inch widths, in 100-foot and 500-foot rolls. The aluminized section is backed by paper, so it doesnt wrinkle much and it can easily be replaced if it gets dirty. Both of these materials are totally opaque, so they can be used as total light barriers.
Mylar is a metallic plastic that is sold at garden shops and other stores. It comes in wide rolls, so it can be installed very quickly. It loses its metallic coating when it is splashed with some chemicals. While it has very high reflectivity, it is not opaque, so a lit garden can be seen through the material.
White polyethylene plastic is inexpensive, fairly reflective, easy to install, and very washable. It comes in many widths and presents a water barrier as well as reflectivity. It is a preferred material. Sometimes it is available in white on one side and black on the other which makes it opaque. It can be used to construct a "room" in a much larger space by hanging or tacking it on a frame. It is easy to work with and can be installed quickly.
White styrofoam insulation boards are extremely reflective and very easy to use. Because they are solid, they can be hung from ceilings with string to create spaces, tacked to a wall or light frame, or leaned against a garden apparatus. They are lightweight and easy to move, and can be restored to their original brightness by washing them with household cleaner
hope this was of help to some of you.be safe all . the postman.
postmandave Reviewed by postmandave on . info on lighting found some stuff on lighting that might be of use to some of the new grower .knock yourselfs out lads and lassies. Plants use light as energy to fuel photosynthesis, a process in which water and carbon dioxide are converted to sugar. Sugar is the basic building block of all plants. Without light, green plants have no way of producing food and they die. By chemically twisting and tweaking the sugar molecule, plants form carbohydrates, which are more complex molecules. With the addition of Rating: 5