High Intensity Discharge HID Lights

Growers use MID lamps to replace natural sunlight indoors and grow outstanding cannabis. High intensity discharge lamps out-perform all other lamps in their lumens-per-watt efficiency, spectral balance, and brilliance. The spectrum and brilliance of HID's help growers replicate growth responses induced in cannabis by natural sunlight. Compare charts on HID spectral emission with the chart on photosynthetic response, chlorophyll synthesis, and positive tro-pism.

The HID lamp family contains mercury vapor, metal halide, High Pressure (HP) sodium, and conversion bulbs. Metal halide, HP sodium, and conversion lamps have a spectrum similar to actual sunshine and can be used to grow marijuana. Mercury vapor lamps were the first HID's on the market. Obsolete mercury vapor lamps are inefficient electrically and produce a poor spectrum for plant growth. Now most all mercury vapor lamps have been retrofitted with more efficient HID's.

Researchers have created a few better bulbs with a higher PAR rating, but there is no new technology in sight. The latest glass covers of the bulbs have become slightly better at letting light through, but there have been very few major technical advances in these bulbs for the last 20 years.

Popular HID wattages include 150, 175, 250, 400, 430, 600, 1000, and 1100. A 1500-watl metal halide is also available but is not practical for growing. The 1500-watt lamp is designed for stadium lighting and generates too much heat and light to be used efficiently indoors. Smaller 3 50-250-watt bulbs are popular for smal) gardens measuring up to three feet square. Brighter 400-1100 lamps are favorites for larger gardens. The 400 and 600-walt bulbs are most popular among European growers. North American growers favor 600 and 1000-watt bulbs. Super efficient 1100-watt metal halides were introduced in 2000.

Incandescent bulbs are the least efficient; 600-watt HP sodium lamps are the most efficient. The brightest bulbs measured in lumens-perwatt are the metal halide and HP sodium bulbs.

Originally developed in the 1970s, metal halides and HP sodium bulbs were characterized by one main technical limitation-the larger the bulb, the higher the lumens-per-watt conversion. For example, watt for watt, a 1000-watt HP sodium produces about 12 percent more light than a 400-watt HPS and about 25 percent more light than a 150-watt HPS. Scientists overcame this barrier when they developed the 600-watt HP sodium. Watt for watt, a 600-watt HPS produces seven percent more light than the 1000-watt HPS. The "pulse start" metal halides are also brighter and much more efficient than their predecessors.

High intensity discharge lamps produce light by passing electricity through vaporized gas enclosed in a clear ceramic arc lube under very high pressure. The dose, or combination of chemicals, sealed in the arc tube determines the color spectrum produced. The mix of chemicals in the arc tube allows metal hatide lamps to yield the broadest and most diverse spectrum of light. The spectrum of HP sodium lamps is somewhat limited because of the narrower band of chemicals used to dose the arc tube. The arc tube is contained within a larger glass bull). Most of the ultraviolet (UV) rays produced iri the arc tube are filtered by the outer bulb. Never look at the arc tube if the outer bulb breaks. Turn off the lamp immediately. Some bulbs have a phosphor coating inside the bulb. This coating makes them produce a little different spectrum and fewer lumens.

General Electric, Iwasaki, Lumenarc, Osram/Sylvania, Philips, and Venture (SunMaster) manufacture HID bulbs. These companies construct many bulbs with the exact same technical statistics. According to some gardeners, certain brands of bulbs are belter than others because of where they are manufactured. They usually came to this conclusion because they purchased two different brands of (1000-watt) bulbs and had better luck using one brand. What these gardeners don't know is that many of the manufacturers buy and use the same components, often manufactured by competitors!

Pulse-start metal halides commonly use 240 volts and harbor the starter in the ballast box, not in the arc tube. These systems employ physically smaller reactor ballasts that keep original line voltage within ten percent of the voltage in the arc tube.

Reflective walls increase light In the growing area. Less intense light on the perimeter of gardens is wasted unless it is reflected back onto foliage. Up to 95 percent of this light can be reflected back toward plants. For example, if 500 foot-candles of light is escaping from the edge of the garden and it is reflected at the rate of 50 percent, then 250 foot-candles will be available on the edge of the garden.

Reflective walls should be 12 inches (30 cm) or less from the plants for optimum reflection. Ideally, take walls to the plants, The easiest way to install mobile walls is to hang the lamp near the corner of a room. Use the two corner walls to reflect light. Move the two outside walls close to plants to reflect light. Make the mobile walls from lightweight plywood, Styrofoarn, or white

Visqueen plastic.

Using white Visqueen plastic to "white out" a room is quick and causes no damage to the room. Visqueen plastic is inexpensive, removable, and reusable. It can be used to fabricate walls and partition rooms. Waterproof Visqueen also protects the walls and floor from water damage. Lightweight Visqueen is easy to cut with scissors or a knife and can be stapled, nailed, or taped.

To make the white walls opaque, hang black Visqueen on the outside. The dead air space between the two layers of Visqueen also increases insulation.

The only disadvantages of white Visqueen plastic are that it is not as reflective as flat white paint, it may get brittle after a few years of use under an HID lamp, and it can be difficult to find at retail outlets.

Using flat white paint is one of the simplest, least expensive, most efficient ways to create optimum reflection. Artists' titanium white paint is more expensive, but more reflective. While easy to clean, semi-gloss white is not quite as reflective as flat white. Regardless of the type of white used, a non-toxic, fungus-inhibiting agent should be added when the paint is mixed. A gallon of good Hat white paint costs less than $25. One or two gallons should be enough to "white out" the average grow room. But do not paint the floor white-the reflection is detrimental to tender leaf undersides. Use a primer coat to prevent bleed-through of dark colors or stains or if walls are rough and unpainted. Install the vent fans before painting. Fumes are unpleasant and can cause health problems. Painting is laborintensive and messy, but it's worth the trouble.

Organic Gardeners Composting

Organic Gardeners Composting

Have you always wanted to grow your own vegetables but didn't know what to do? Here are the best tips on how to become a true and envied organic gardner.

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