ballast

jogameagua

Member
hello, can somebody tell me if i need to usa a ballast for a 250w hps lamp and what does the ballst exactly?

thank you very much for any help, i'm starting to grow :D
 

cannabis420420

Well-Known Member
hello, can somebody tell me if i need to usa a ballast for a 250w hps lamp and what does the ballst exactly?

thank you very much for any help, i'm starting to grow :D
A light bulb is really quite simple. Have you ever seen pictures of molten steel being poured? If you have, you will notice that it is glowing white-hot. A light bulb is simply a small metal wire that is glowing with heat. In this case, the metal is tungsten (W on the Periodic Table). This is important because tungsten is solid at very high temperatures. A light bulb also has most of the air sucked out of it. If it didn't, the wire would actually burn up instantly. When a light bulb "burns out", it is because the filament slowly vaporizes; the black on the inside of a burned out lightbulb is really just resolidified metal vapor.

Now back to how a lightbulb works. Electricity flowing through the wire causes it to heat up. This heat makes it glow. It heats up because of a concept called resistance. When electricity passes through something, the substance it is passing through tries to hold on to the electrons. The electrons have to be forced through. Some of this force is absorbed by the metal and given off as heat. As the filament heats up, it gives off light.



The heat energy goes into electrons of the tungsten atoms. The energy pushes the electrons farther away from the nucleus of the atoms. As the electrons fall back, they give off photons, little bits of light.

Fluorescent light bulbs work similarly. Electricity moves in pulses through a tube. The electricity hits special molecules inside the tube and their electrons are knocked away. As their electrons fall back, light is given off. In this case, the electrons are knocked off by electrictiy, not heat, and therefore, fluorescent light bulbs can be cooler. Since they are cooler, nothing vaporizes, and the fluorescent light bulb lasts longer.

I hope I answered your question without confusing you too much.
 

cannabis420420

Well-Known Member
hello, can somebody tell me if i need to usa a ballast for a 250w hps lamp and what does the ballst exactly?

thank you very much for any help, i'm starting to grow :D
Types of lamps used as grow lights include incandescents, fluorescent lamps, high-intensity discharge lamps, and LEDs.
Today, the most widely used lights for professional indoor flower and vegetable growing are HPS/SON (high pressure sodium) and MH (metal halide). These are types of HID or high-intensity discharge lamps. Normal metal halide bulbs have a slightly bluish light and are used for the vegetative phase of growth, as their spectrum is close to sunlight and encourages normal to slightly leggy growth. Unlike high pressure sodium lamps, metal halide lamps also produce ultraviolet radiation, which may play a role in increasing the amount, quality, and potency of herbs or other materials produced by plants. High pressure sodium lamps may trigger a greater flowering response in plants and are thus used for the second (or reproductive) phase of growth.[1] If high pressure sodium lamps are used for the vegetative phase, plants will usually grow slightly more quickly, but will also have longer internodes, and may be longer overall. Metal halide bulbs with added reddish spectrum as well as high pressure sodium bulbs with added bluish spectrum are also available for added flexibility for use with both vegetative and flowering growth.[2]
[edit]Incandescent grow lights
Incandescent grow lights have a red-yellowish tone and low color temperature (approx. 2700 K). They are used to highlight indoor plant groupings and not as a true plant 'growing' light (although they may be labeled as such). Incandescent growing lamps have an average life span of 750 hours. In addition, they are less energy efficient than fluorescent or high-intensity discharge lamps, converting much of the electricity consumed into heat (rather than light).
[edit]Fluorescent grow lights
Today,fluorescents lights are available in any desired color temperature in the range from 2700 K to 6500 K. Standard fluorescents are usually used for growing vegetables (as leaf lettuce, spinach, and herbs) or for starting seedlings to get a jump start on spring plantings. Standard fluorescents produce twice as many lumens per watt of energy consumed as incandescents and have an average usable life span of up to 20,000 hours. This is 25 times as long as an incandescent. Cool white fluorescent lamps are sometimes used as grow lamps. These offer slightly lower performance, a white light, and lower purchase cost.
High Output fluorescents produce twice as much light as standard fluorescent lamps. A HO fluorescent fixture has a very thin profile, making it extremely useful in vertically limited areas. High Output fluorescents produce about 5,000 lumens per 54 watt bulb and are available in warm (2700 K) and cool (6500 K) versions. Usable life span for High Output fluorescent lamps is about 10,000 hours.
Compact fluorescents are smaller versions of fluorescent lamps and are used for propagation, as well as for growing larger plants. Compact fluorescents work in specially designed reflectors that efficiently direct light to plants, much like the HID lamps below. Compact fluorescent bulbs are also available in warm/ red (2700K), full spectrum or daylight (5000K) and cool/ blue (6500K) versions. Usable life span for compact fluorescent grow lamps is about 10,000 hours.
High Output Fluorescent/HID hybrids combine cool burning with the penetration of high intensity discharge technology. The primary advantages to these fixtures is their blend of light colors and broad even coverage. In addition, electricity costs are substantially less than with incandescent lighting.
[edit]High-pressure sodium lamps
High pressure sodium lamps yield yellow lighting (2200K) and have a very poor color rendering index of 22. They are used for the second (or reproductive) phase of the growth. If high pressure sodium lamps are used for the vegetative phase, plants will usually grow slightly more quickly. The major drawback to growing under high pressure sodium alone is that the plants tend to be taller and leggier with a longer internodal length than plants grown under metal halide. . They are used in less color critical applications such as parking lots, street lights and for supplemental greenhouse lighting. The benefit of high pressure sodium lamps to the horticultural industry is their ability to enhance the fruiting and flowering process in plants. Orange/red spectrum HPS is the spectrum plants use in their reproductive processes, which generally produces larger harvests of higher quality herbs, vegetables, fruits or flowers. Sometimes the plants grown under these lamps do not appear very healthy (although they usually are). This is due to the poor color rendering of high pressure sodium, which makes the plants look pale, washed out or nitrogen starved. Benefits to high pressure sodium lighting are their incredibly long usable bulb life (up to two years in many cases); and unparalleled efficiency at six times more light output per watt of energy consumed than a standard incandescent grow lamp. Due to their high efficiency and the fact that plants grown in greenhouses get all the blue light they need naturally, these lamps are the preferred supplemental greenhouse lights. But, in the higher latitudes, there are periods of the year where sunlight is scarce, and additional sources of light (aside from HPS illumination) are indicated for proper growth. It also ought to be noted that HPS lamps may cause distinctive infrared and optical signatures, which can attract insects or other species of pests; these may in turn threaten the various herbs, flowers, or vegetables being grown. High pressure sodium lamps emit a lot of heat which can cause leggier growth, this is typically controlled by using special air cooled bulb reflector/enclosures.
[edit]Combination HPS/MH lamps
Combination HPS/MH lamps combine a metal halide bulb and a high pressure sodium bulb in the same reflector, either with a single integrated ballast assembly or two separate ballast assemblies. The combination of blue metal halide light and red high pressure sodium light is said by manufacturers to create an ideal spectral blend and extremely high outputs, but in reality it is a compromise on both situations. These types of lights usually cost quite a bit more than a standard light and have a shorter life span. Also because they use two smaller lights rather than one larger light the distance that the light penetrates is significantly shorter, in comparison to a regular hid bulb, due to the inverse-square law of light.
[edit]Switchable, convertible & two-way lamps
Switchable, Two-Way and convertible lamps are used to burn either a metal halide bulb or an equivalent wattage high pressure sodium bulb in the same fixture, but not at the same time. These fixtures are used for propagating and vegetatively growing plants under the metal halide, then switching to a high pressure sodium bulb for the fruiting or flowering stage of plant growth. To change between the lamps, only the bulb needs changing and a switch needs to be set to the appropriate setting. These are commonly known as conversion bulbs and usually a metal halide conversion bulb will be used in an HPS ballast since the MH conversion bulbs are more common.
[edit]LED grow lamps


LED panel light source used in an experiment on plant growth by NASA. Pictured plant is a potato plant.
Recent advancements in LEDs have allowed for the production of relatively cheap, bright, and long lasting grow lights that emit only the wavelengths of light corresponding to chlorophyll's absorption peaks. These lights are attractive to indoor growers since they do not consume as much power, do not require ballasts, and produce a fraction of the heat of HID lamps. Since there is a significant reduction in heat, time can be extended between watering cycles because the plants transpire less under LED grow lights. A caution is warned to those growing with LEDs not to over water the plants.
There are four chlorophyll absorption peaks and LED grow lights use four different types of LEDs to hit all four peaks (two red and two blue).[3] Early LED grow lamps used hundreds of 1 or 2 watt LEDs and were not effective replacements for HID lamps. Newer advanced LED grow lamps use automotive grade 6 watt LEDs and have shown similar results to HID lamps.
Though results will vary by plant species, a general example follows below: 90W LED Light can replace a 400W Metal Halide(High intensity discharge or HID) /High Pressure Sodium grow light, a 120W LED Light can replace a 600-800W Metal Halide/HPS grow light, a 300W LED Light can replace a 1330W Metal Halide/HPS grow light, and a 600W LED Light can replace a 1600W-2000W HPS/HID lights light Most LED lights are designed for indoor growing ONLY.[4]
[edit]Use

Grow lights are usually used for indoor gardening, plant propagation and food production, including indoor hydroponics and aquatic plants. Although most grow lights are used on an industrial level, some small-scale/domestic usage of these lamps has also been found.
According to the inverse square law, the intensity of light radiating from a point source (in this case a bulb) that reaches a surface is inversely proportional to the square of the surface's distance from the source. So if an object is twice as far away, it receives only 1/4 the light. This is a serious hurdle for indoor growers, and many techniques are employed to use light as efficiently as possible. Reflectors are thus often used in the lamps to maximize light efficiency. Plants or lights are moved as close together as possible so that they receive equal lighting and that all light coming from the lamps wind up on the plants (rather than partly besides it). Often, the distance between lamp and plant is in the range of 24 inches (with incandescent lamps), up to 4 inches (with other lamps as compact, large and high-output fluorescent lamps).[5] Many home gardeners cover the walls of their grow-room with a reflective material, or alternatively, white paint to maximize efficiency.
[edit]Light requirements of plants

To determine the appropriate lighting (and the lamp to be best used), the specific needs of the plant need to be determined. To arrange optimum lighting, the lighting present in the plant's natural environment need to be imitated. Of course, the bigger the plant gets the more light it requires; if there is not enough light, a plant will not grow, regardless of other conditions.[6]
For example vegetables grow best in full sunlight, which means in practice that as much light as possible must be supplied to grow vegetables indoors (fluorescent lamps, or MH-lamps are thus preferred). Foliage plants (e.g. Philodendron) grow in full shade and can therefore grow normally with relatively little artificial light (thus for the latter, regular incandescents may already suffice).
In addition, plants also require both dark and light ("photo"-) periods.[7] Therefore, lights need to be timed to switch them on and off at set intervals. The optimum photo/dark period depends specifically on the species and variety of plant (some prefer long days and short nights and others prefer the opposite, or something in between).
For indoor gardening, one of the most important topics is light density, measured in lux. Light density is the amount of light incident on a surface. One lux equals one lumen (unit) of light falling on an area of one square meter. A brightly lit office would be illuminated at about 400 lux. In Imperial (pounds-feet) terms, a foot-candle, or the intensity of a standard candle on an area of 1 square foot, is about 10.76 lux. In professional farming PAR watt or microeinstein per squaremeter second is used instead of lux, because lux is optimized for human vision, not for photosynthesis, and can be very misleading in case of non-white lightsources, like the purplish-looking LED growlights.
 

cannabis420420

Well-Known Member
Types of lamps used as grow lights include incandescents, fluorescent lamps, high-intensity discharge lamps, and LEDs.
Today, the most widely used lights for professional indoor flower and vegetable growing are HPS/SON (high pressure sodium) and MH (metal halide). These are types of HID or high-intensity discharge lamps. Normal metal halide bulbs have a slightly bluish light and are used for the vegetative phase of growth, as their spectrum is close to sunlight and encourages normal to slightly leggy growth. Unlike high pressure sodium lamps, metal halide lamps also produce ultraviolet radiation, which may play a role in increasing the amount, quality, and potency of herbs or other materials produced by plants. High pressure sodium lamps may trigger a greater flowering response in plants and are thus used for the second (or reproductive) phase of growth.[1] If high pressure sodium lamps are used for the vegetative phase, plants will usually grow slightly more quickly, but will also have longer internodes, and may be longer overall. Metal halide bulbs with added reddish spectrum as well as high pressure sodium bulbs with added bluish spectrum are also available for added flexibility for use with both vegetative and flowering growth.[2]
[edit]Incandescent grow lights
Incandescent grow lights have a red-yellowish tone and low color temperature (approx. 2700 K). They are used to highlight indoor plant groupings and not as a true plant 'growing' light (although they may be labeled as such). Incandescent growing lamps have an average life span of 750 hours. In addition, they are less energy efficient than fluorescent or high-intensity discharge lamps, converting much of the electricity consumed into heat (rather than light).
[edit]Fluorescent grow lights
Today,fluorescents lights are available in any desired color temperature in the range from 2700 K to 6500 K. Standard fluorescents are usually used for growing vegetables (as leaf lettuce, spinach, and herbs) or for starting seedlings to get a jump start on spring plantings. Standard fluorescents produce twice as many lumens per watt of energy consumed as incandescents and have an average usable life span of up to 20,000 hours. This is 25 times as long as an incandescent. Cool white fluorescent lamps are sometimes used as grow lamps. These offer slightly lower performance, a white light, and lower purchase cost.
High Output fluorescents produce twice as much light as standard fluorescent lamps. A HO fluorescent fixture has a very thin profile, making it extremely useful in vertically limited areas. High Output fluorescents produce about 5,000 lumens per 54 watt bulb and are available in warm (2700 K) and cool (6500 K) versions. Usable life span for High Output fluorescent lamps is about 10,000 hours.
Compact fluorescents are smaller versions of fluorescent lamps and are used for propagation, as well as for growing larger plants. Compact fluorescents work in specially designed reflectors that efficiently direct light to plants, much like the HID lamps below. Compact fluorescent bulbs are also available in warm/ red (2700K), full spectrum or daylight (5000K) and cool/ blue (6500K) versions. Usable life span for compact fluorescent grow lamps is about 10,000 hours.
High Output Fluorescent/HID hybrids combine cool burning with the penetration of high intensity discharge technology. The primary advantages to these fixtures is their blend of light colors and broad even coverage. In addition, electricity costs are substantially less than with incandescent lighting.
[edit]High-pressure sodium lamps
High pressure sodium lamps yield yellow lighting (2200K) and have a very poor color rendering index of 22. They are used for the second (or reproductive) phase of the growth. If high pressure sodium lamps are used for the vegetative phase, plants will usually grow slightly more quickly. The major drawback to growing under high pressure sodium alone is that the plants tend to be taller and leggier with a longer internodal length than plants grown under metal halide. . They are used in less color critical applications such as parking lots, street lights and for supplemental greenhouse lighting. The benefit of high pressure sodium lamps to the horticultural industry is their ability to enhance the fruiting and flowering process in plants. Orange/red spectrum HPS is the spectrum plants use in their reproductive processes, which generally produces larger harvests of higher quality herbs, vegetables, fruits or flowers. Sometimes the plants grown under these lamps do not appear very healthy (although they usually are). This is due to the poor color rendering of high pressure sodium, which makes the plants look pale, washed out or nitrogen starved. Benefits to high pressure sodium lighting are their incredibly long usable bulb life (up to two years in many cases); and unparalleled efficiency at six times more light output per watt of energy consumed than a standard incandescent grow lamp. Due to their high efficiency and the fact that plants grown in greenhouses get all the blue light they need naturally, these lamps are the preferred supplemental greenhouse lights. But, in the higher latitudes, there are periods of the year where sunlight is scarce, and additional sources of light (aside from HPS illumination) are indicated for proper growth. It also ought to be noted that HPS lamps may cause distinctive infrared and optical signatures, which can attract insects or other species of pests; these may in turn threaten the various herbs, flowers, or vegetables being grown. High pressure sodium lamps emit a lot of heat which can cause leggier growth, this is typically controlled by using special air cooled bulb reflector/enclosures.
[edit]Combination HPS/MH lamps
Combination HPS/MH lamps combine a metal halide bulb and a high pressure sodium bulb in the same reflector, either with a single integrated ballast assembly or two separate ballast assemblies. The combination of blue metal halide light and red high pressure sodium light is said by manufacturers to create an ideal spectral blend and extremely high outputs, but in reality it is a compromise on both situations. These types of lights usually cost quite a bit more than a standard light and have a shorter life span. Also because they use two smaller lights rather than one larger light the distance that the light penetrates is significantly shorter, in comparison to a regular hid bulb, due to the inverse-square law of light.
[edit]Switchable, convertible & two-way lamps
Switchable, Two-Way and convertible lamps are used to burn either a metal halide bulb or an equivalent wattage high pressure sodium bulb in the same fixture, but not at the same time. These fixtures are used for propagating and vegetatively growing plants under the metal halide, then switching to a high pressure sodium bulb for the fruiting or flowering stage of plant growth. To change between the lamps, only the bulb needs changing and a switch needs to be set to the appropriate setting. These are commonly known as conversion bulbs and usually a metal halide conversion bulb will be used in an HPS ballast since the MH conversion bulbs are more common.
[edit]LED grow lamps


LED panel light source used in an experiment on plant growth by NASA. Pictured plant is a potato plant.
Recent advancements in LEDs have allowed for the production of relatively cheap, bright, and long lasting grow lights that emit only the wavelengths of light corresponding to chlorophyll's absorption peaks. These lights are attractive to indoor growers since they do not consume as much power, do not require ballasts, and produce a fraction of the heat of HID lamps. Since there is a significant reduction in heat, time can be extended between watering cycles because the plants transpire less under LED grow lights. A caution is warned to those growing with LEDs not to over water the plants.
There are four chlorophyll absorption peaks and LED grow lights use four different types of LEDs to hit all four peaks (two red and two blue).[3] Early LED grow lamps used hundreds of 1 or 2 watt LEDs and were not effective replacements for HID lamps. Newer advanced LED grow lamps use automotive grade 6 watt LEDs and have shown similar results to HID lamps.
Though results will vary by plant species, a general example follows below: 90W LED Light can replace a 400W Metal Halide(High intensity discharge or HID) /High Pressure Sodium grow light, a 120W LED Light can replace a 600-800W Metal Halide/HPS grow light, a 300W LED Light can replace a 1330W Metal Halide/HPS grow light, and a 600W LED Light can replace a 1600W-2000W HPS/HID lights light Most LED lights are designed for indoor growing ONLY.[4]
[edit]Use

Grow lights are usually used for indoor gardening, plant propagation and food production, including indoor hydroponics and aquatic plants. Although most grow lights are used on an industrial level, some small-scale/domestic usage of these lamps has also been found.
According to the inverse square law, the intensity of light radiating from a point source (in this case a bulb) that reaches a surface is inversely proportional to the square of the surface's distance from the source. So if an object is twice as far away, it receives only 1/4 the light. This is a serious hurdle for indoor growers, and many techniques are employed to use light as efficiently as possible. Reflectors are thus often used in the lamps to maximize light efficiency. Plants or lights are moved as close together as possible so that they receive equal lighting and that all light coming from the lamps wind up on the plants (rather than partly besides it). Often, the distance between lamp and plant is in the range of 24 inches (with incandescent lamps), up to 4 inches (with other lamps as compact, large and high-output fluorescent lamps).[5] Many home gardeners cover the walls of their grow-room with a reflective material, or alternatively, white paint to maximize efficiency.
[edit]Light requirements of plants

To determine the appropriate lighting (and the lamp to be best used), the specific needs of the plant need to be determined. To arrange optimum lighting, the lighting present in the plant's natural environment need to be imitated. Of course, the bigger the plant gets the more light it requires; if there is not enough light, a plant will not grow, regardless of other conditions.[6]
For example vegetables grow best in full sunlight, which means in practice that as much light as possible must be supplied to grow vegetables indoors (fluorescent lamps, or MH-lamps are thus preferred). Foliage plants (e.g. Philodendron) grow in full shade and can therefore grow normally with relatively little artificial light (thus for the latter, regular incandescents may already suffice).
In addition, plants also require both dark and light ("photo"-) periods.[7] Therefore, lights need to be timed to switch them on and off at set intervals. The optimum photo/dark period depends specifically on the species and variety of plant (some prefer long days and short nights and others prefer the opposite, or something in between).
For indoor gardening, one of the most important topics is light density, measured in lux. Light density is the amount of light incident on a surface. One lux equals one lumen (unit) of light falling on an area of one square meter. A brightly lit office would be illuminated at about 400 lux. In Imperial (pounds-feet) terms, a foot-candle, or the intensity of a standard candle on an area of 1 square foot, is about 10.76 lux. In professional farming PAR watt or microeinstein per squaremeter second is used instead of lux, because lux is optimized for human vision, not for photosynthesis, and can be very misleading in case of non-white lightsources, like the purplish-looking LED growlights.
hope this helps you :weed::weed::weed::weed::weed::weed::weed::weed::weed::weed::weed::weed::joint::joint::joint::joint::joint::joint::joint::joint::joint::joint::joint::joint::joint::joint::joint::joint::joint::joint::joint::joint:bongsmiliebongsmiliebongsmiliebongsmiliebongsmiliebongsmiliebongsmiliebongsmiliebongsmiliebongsmilie:bigjoint::bigjoint::bigjoint::bigjoint::bigjoint::bigjoint::bigjoint::bigjoint::leaf::leaf::leaf::leaf::leaf::leaf::leaf::leaf::blsmoke::blsmoke::blsmoke::blsmoke:bongsmiliebongsmiliebongsmilie:eyesmoke::eyesmoke::eyesmoke::eyesmoke::weed::weed::weed::weed::weed::joint::joint::joint::joint::joint::mrgreen::mrgreen::mrgreen::mrgreen::mrgreen::mrgreen:+rep
 

jogameagua

Member
ok, nice information, really helpfull. but i still don't know if i really need a ballast and what does it do..

thank for any more information.
 

Drifter126

Active Member
A ballast is a transformer that puts out the correct voltage for a specfic type of bulb.And yes you will need a ballast....
 

dadio161

Well-Known Member
Yes you need one . You can not light your 250W light bulb without one.
Some light fixtures can have a built in ballast.
 

SnakierGrizzly

Well-Known Member
i didnt think the ballast ran the light i just thought that was an aluminum thing hanging above the HID that reflected the light to the plants
 

WeeGogs

Active Member
A light bulb is really quite simple. Have you ever seen pictures of molten steel being poured? If you have, you will notice that it is glowing white-hot. A light bulb is simply a small metal wire that is glowing with heat. In this case, the metal is tungsten (W on the Periodic Table). This is important because tungsten is solid at very high temperatures. A light bulb also has most of the air sucked out of it. If it didn't, the wire would actually burn up instantly. When a light bulb "burns out", it is because the filament slowly vaporizes; the black on the inside of a burned out lightbulb is really just resolidified metal vapor.

Now back to how a lightbulb works. Electricity flowing through the wire causes it to heat up. This heat makes it glow. It heats up because of a concept called resistance. When electricity passes through something, the substance it is passing through tries to hold on to the electrons. The electrons have to be forced through. Some of this force is absorbed by the metal and given off as heat. As the filament heats up, it gives off light.



The heat energy goes into electrons of the tungsten atoms. The energy pushes the electrons farther away from the nucleus of the atoms. As the electrons fall back, they give off photons, little bits of light.

Fluorescent light bulbs work similarly. Electricity moves in pulses through a tube. The electricity hits special molecules inside the tube and their electrons are knocked away. As their electrons fall back, light is given off. In this case, the electrons are knocked off by electrictiy, not heat, and therefore, fluorescent light bulbs can be cooler. Since they are cooler, nothing vaporizes, and the fluorescent light bulb lasts longer.

I hope I answered your question without confusing you too much.

Except for 1 thing, these Lamps work with high pressure gas, so they have no internal filament and the gas needs to be ignited by an ignitor the same way as a flourescent tube light, but the high pressure gas needs a ballast to give it a constant high boost of electric power to keep it ignited exactly the same way as a large flourescent tube you have on your kitchen ceiling you will see the small starter (ignitor) on the side of the box that supports the tube and the small choke (ballast) is inside that keeps the gas ignited inside the tube but there are three differences if you break a monofilament light bulb while lit it will implode as there is negative pressure inside (no air) so it will pop, if you take the cover off your flourescent tube and when it has been on for 15 minutes whack the tube with a brush handle there will be a large popping/banging noise and a shower of glass. if you break the high pressure lamp, that is the smaller long white lamp on the inside of the large glass hps light bulb when it is ignited and it explodes it will kill you like a grenade going off in a shoebox. hence the need for protective steel boxes and toughened safety glass for these lamps. with metal halide the little white bulb inside is more rounded. so the moral of the story buy a ballast a bulb and a good solid lamp unit cover to protect your hps bulb from you and to protect you from your hps bulb.
 
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