taken from another site
"There are 2 types of HID grow lights used for indoor marijuana growing, high pressure sodium (HPS) and metal halide (MH). These come in a range of sizes, the most common being 175 Watts, 250 Watts, 400 Watts, 600 Watts and 1000 Watts. Anything over these size bulbs become less efficient for growing and you should consider using multiple sets of smaller bulbs, we even suggest that at the 1,000 Watt level.
Lamp Type Watts Lumens /bulb Total efficiency
Metal Halide (MH) 400 36,000 36k lumens
High Pressure Sodium (HPS) 400 45,000 45k lumens
The size of bulb you purchase will depend on how many plants you want to grow. This varies widely, depending on the strain of marijuana and on how much vegetative growth you want them to have. It is better to calculate your requirements by area and a rough guide would be:
250 watt bulb will supply enough light to cover a 2.5’ x 2.5’ (75cm X 75cm) area (6 plants or fewer)
400 watt bulb will supply enough light to cover a 4’ x 4’ (120cm X 120cm) area (12 plants or fewer)
600 watt bulb will supply enough light to cover a 5’ x 5’ (150cm x 150cm) area (18 plants or fewer)
1,000 watt bulb will supply enough light to cover a 6.5’ x 6.5’ (2m X 2m) area (30 plants or fewer)
High intensity discharge (HID) grow lights can provide light in the right spectrums used by marijuana plants to grow successfully without sunlight if used in conjunction with each other.
High pressure sodium (HPS) grow lights used to be one of the most efficient methods of turning electricity into usable light. These days LED grow lights offer a far better use of power. HPS grow lights work well, are cheaper to buy upfront but produce a lot of heat which has to be managed and their bulbs and ballasts have to be changed far more regularly than LEDs. HPS grow lights operate in the warmer colors, yellow, amber, orange and reds which are most useful for marijuana flowering (budding). HPS lights are deficient in the blue spectrum but their amber to reds light bands triggers hormones in the marijuana plant to start the flowering stage. HPS are great for supplemental lighting and often last far longer than a similar MH light.
Metal halide (MH) grow lights produce light in the blue / green spectrums and are more useful in the vegetation stage. They grow the plants leaves and stem, make it big and ready for flowering. These bulbs will last anywhere from 3,000 to 10,000 hours depending on how many times they are turned on and off and the brand or quality of the bulb."
https://en.wikipedia.org Metal-halide lamp
https://en.wikipedia.org High pressure sodium
If you purchase a ballast you should get a dimable digital ballast, digital ballasts are more efficient then magnetic ballasts. with a digital ballast you can run either a Metal Halide light bulb for vegetative growth or a High Pressure Sodium light bulb for flowering. you will need to purchase a dimable digital ballast in whatever wattage you wish, a Metal Halide light bulb in whatever wattage, a High Pressure Sodium light bulb in whatever wattage, a light reflector (I recommend a cooltube light reflector), possibly a ballast cord to connect the ballast to the reflector, a 6 inch inline fan, ducting, possibly a carbon filter if you wish to scent control, chain or yo-yo's to hang the lights and equipment. have a look at how I have my equipment set up for my KingJohnC 400 Watt LA Confidential Seed Cabinet Soil Indoor grow journal.
KingJohnC's 400 Watt LA Confidential Seed Cabinet Soil Indoor Grow Journal
"There are 2 types of HID grow lights used for indoor marijuana growing, high pressure sodium (HPS) and metal halide (MH). These come in a range of sizes, the most common being 175 Watts, 250 Watts, 400 Watts, 600 Watts and 1000 Watts. Anything over these size bulbs become less efficient for growing and you should consider using multiple sets of smaller bulbs, we even suggest that at the 1,000 Watt level.
Lamp Type Watts Lumens /bulb Total efficiency
Metal Halide (MH) 400 36,000 36k lumens
High Pressure Sodium (HPS) 400 45,000 45k lumens
The size of bulb you purchase will depend on how many plants you want to grow. This varies widely, depending on the strain of marijuana and on how much vegetative growth you want them to have. It is better to calculate your requirements by area and a rough guide would be:
250 watt bulb will supply enough light to cover a 2.5’ x 2.5’ (75cm X 75cm) area (6 plants or fewer)
400 watt bulb will supply enough light to cover a 4’ x 4’ (120cm X 120cm) area (12 plants or fewer)
600 watt bulb will supply enough light to cover a 5’ x 5’ (150cm x 150cm) area (18 plants or fewer)
1,000 watt bulb will supply enough light to cover a 6.5’ x 6.5’ (2m X 2m) area (30 plants or fewer)
High intensity discharge (HID) grow lights can provide light in the right spectrums used by marijuana plants to grow successfully without sunlight if used in conjunction with each other.
High pressure sodium (HPS) grow lights used to be one of the most efficient methods of turning electricity into usable light. These days LED grow lights offer a far better use of power. HPS grow lights work well, are cheaper to buy upfront but produce a lot of heat which has to be managed and their bulbs and ballasts have to be changed far more regularly than LEDs. HPS grow lights operate in the warmer colors, yellow, amber, orange and reds which are most useful for marijuana flowering (budding). HPS lights are deficient in the blue spectrum but their amber to reds light bands triggers hormones in the marijuana plant to start the flowering stage. HPS are great for supplemental lighting and often last far longer than a similar MH light.
Metal halide (MH) grow lights produce light in the blue / green spectrums and are more useful in the vegetation stage. They grow the plants leaves and stem, make it big and ready for flowering. These bulbs will last anywhere from 3,000 to 10,000 hours depending on how many times they are turned on and off and the brand or quality of the bulb."
https://en.wikipedia.org Metal-halide lamp
https://en.wikipedia.org High pressure sodium
If you purchase a ballast you should get a dimable digital ballast, digital ballasts are more efficient then magnetic ballasts. with a digital ballast you can run either a Metal Halide light bulb for vegetative growth or a High Pressure Sodium light bulb for flowering. you will need to purchase a dimable digital ballast in whatever wattage you wish, a Metal Halide light bulb in whatever wattage, a High Pressure Sodium light bulb in whatever wattage, a light reflector (I recommend a cooltube light reflector), possibly a ballast cord to connect the ballast to the reflector, a 6 inch inline fan, ducting, possibly a carbon filter if you wish to scent control, chain or yo-yo's to hang the lights and equipment. have a look at how I have my equipment set up for my KingJohnC 400 Watt LA Confidential Seed Cabinet Soil Indoor grow journal.
KingJohnC's 400 Watt LA Confidential Seed Cabinet Soil Indoor Grow Journal
