MMAD HYDROPONICS - Lighting FAQ's

FAQ's Of Sun & Lighting Glossary.


Sun FAQ & Lighting Glossary

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First, lets talk about the sun. (SUN FAQ). or Go directly to Light Glossary

  1. Which is a better lamp to grow with MH or HPS; I'm on a limited budget and can only afford one?
  2. How long does the average 1000 watt HPS lamp last?
  3. Is it worth the investment to upgrade to a full spectrum bulb rather than the standard bulbs?
  4. Which Bulb should be used in the Vegetative stage and which one in the bloom?
  5. Based on Lumen per watt Ratio what is more efficient to operate, MH or HPS?
  6. Can I run a 1000 watt MH bulb wired up to a socket and just plug it in my wall plug?
  7. What should my light cycle be for growing indoors?
  8. What is a Lumen?
  9. What is Lux mean?
  10. What is the average lumen per watt ratio of an HPS and MH?
  11. What is the definition of PAR?
  12. What is the PAR value?
  13. When the lights are off what's going on with my plants? Do plants sleep, what happens when the lights are off?
  14. How high should my lights be from the tops of my plants?
  15. What is the Kelvin rating on a bulb mean?
  16. Can I use a green light in my grow room in the dark cycle? Is it true that green light won't wake up my plants?
  17. What is a more efficient reflector to use if my lamp is universal, horizontal or vertical?
  18. What is a good application for the parabolic reflector?
  19. How efficient are Parabolic reflectors?
  20. What is a light mover? Are they beneficial to a grow room?
  21. My ballast seems to operating at a high temperature, but how can I know if it's too hot?
  22. Does the heat coming off of my ballasts make a big difference in my grow room?
  23. What is the most efficient lamp to operate?
  24. What is the best position to have my ballasts in?

Light layout design ideas for your grow room "find it here"

Answers to Sun questions.
  1. Q. Which is a better lamp to grow with MH or HPS; I'm on a limited budget and can only afford one?
    A. I would recommend purchasing the Metal Halide kit, and when it comes into the bloom stage you purchase an HPS conversion lamp or a full spectrum MH lamp. If you are only going to use one type of bulb for flowering and vegetative stages the Sun Master neutral deluxe is an excellent lamp for both purposes. This will be more economical for setting up on a limited budget.
  2. Q. How long does the average 1000 watt HPS lamp last?
    A. On average they burn for 12000 hrs but most gardeners replace once a year more maximum efficiency from the lamp. The cost of new bulbs is minor in comparison to yield loss from weakened lamps. The best way to monitor a bulbs wear is with a light meter. These can be expensive any where from 100$ - 300$ range but for a larger scale set up it is wise investment.
  3. Q. Is it worth the investment to upgrade to a full spectrum bulb rather than the standard bulbs?
    A. While the standard bulbs perform very well, I have seen firsthand the benefit of full spectrum lamps such as Hortilux, Solarmax and Sunmaster and can say with confidence these lamps are definitely worth every penny. But if you are on a limited budget and you buy the clears you will still get excellent results as they are still a very high quality lamp. The full spectrum bulbs give you a combination of red and blue light similar to HPS and MH mixed together which is best for optimum growth.
  4. Q. Which Bulb should be used in the Vegetative stage and which one in the bloom?
    A. Use a Lamp with a high output in the blue range of the spectrum for the vegetative stage and for the flowering stage use a lamp with a high out put in the red range of the spectrum. During all stages of growth but especially during the bloom stage plants require a balanced mix of blue and red for optimal growth.
  5. Q. Based on Lumen per watt Ratio what is more efficient to operate, MH or HPS?
    A. HPS gives a higher lumen per watt ratio than metal halide and the bulbs often last up to twice as long. The 600 watt HPS has the highest lumen per watt ratio of any HID bulb. But for growing MH has a higher PAR value than HPS but often isn't enough in the red range of the spectrum, this is why a mix of both is required for optimal growth. Or the use of full spectrum bulbs is replacing mixing the MH with the HPS. The bulb manufacturers are doing this for you.
  6. Q. Can I run a 1000 watt MH bulb wired up to a socket and just plug it in my wall plug?
    A. Absolutely NO, NO and NO!!! You have to use a 1000 watt MH ballast to power this lamp. The power coming out of your wall must be transformed to usable voltage by the lamp. This is the job of the ballast.
  7. Q. What should my light cycle be for growing indoors?
    A. Since plants all have a different requirement of light that will depend one what type of plants you intend to grow. The best thing to do would be research the plant you wish to grow and find out its light requirements. Most gardeners use an 18 hours of light, 6 hours in the dark cycle for the vegetative stage and a 12 hours of light, 12 hours of the dark cycle for the blooming stage. IMPORTANT NOTE: There is a folllowing out there "radicals" that for some that believe that you can benefit in the grow cycle by running a 24 / 7 light cycle "24 hrs a day, 7 days a week" for the duration of the vegetative state. See question #13 as to why you should not do this!
  8. Q. What is a Lumen?
    A. A lumen is a measurement of light. In simpler terms one lumen is equal to the amount of light that 1 candle will emit on 1 square foot, 1 foot away from the flame. 1 lumen = 1 foot candle
  9. Q. What is Lux mean?
    A. Lux is the metric unit equal to the amount of light falling on one square meter 1 lumen = 10 lux A lux is only 1 / 10 th of a lumen
  10. Q. What is the average lumen per watt ratio of an HPS and MH?
    A. HPS - 140,000 lumens per watt MH - 100,000 lumens per watt Fluorescent - 83,000 lumens per watt Mercury Vapor - 63,000 lumens per watt Incandescent - 17,500 lumens per watt
  11. Q. What is the definition of PAR?
    A. PAR stands for Photosynthetically Active Radiation
  12. Q. What is the PAR value?
    A. PAR value is the amount of light usable by the plants
  13. Q. When the lights are off what's going on with my plants? Obviously they don't just sleep so what do they do?
    A. In the dark cycle the plant shifts its focus from leaf production to root production. The leaves transfer extra stored energy down to the branches and roots. The plants dark cycle is very important. 24 hour light cycles are not the way to go despite radical theories and tests.
  14. Q. How high should my lights be from the tops of my plants?
    A. The lamp should be 18 - 24 inches away from the tops. Use an oscillating fan to circulate air on the tops of your plants. This will help with the removal of heat produced by your lamp and also deliver fresh air across the undersides of your leaves which are where the plant breathes in through tiny microscopic pores called Stomata.
  15. Q. What is the Kelvin rating on a bulb mean?
    A. Kelvin is the unit of measurement expressing color temperature. Each lamp has an aggregate Kelvin temperature that indicates the bulbs spectral output. For indoor gardening a bulb with a Kelvin rating between 3000-6000 will be sufficient
  16. Q. Can I use a green light in my grow room in the dark cycle? I've heard that green light won't wake up my plants?
    A. Yes you can use a green light in your grow room. Plants do not respond to the green range of the spectrum.
  17. Q. What is a more efficient reflector to use if my lamp is universal, horizontal or vertical?
    A. Definitely horizontal. Horizontal reflectors can reflect up to 40 % more light back down to the growing area. The light from a bulb is emitted form the arc tube located in the center of the lamp. If it is burning in the horizontal position, half of this light is being directed at the plants while the other half is being reflected back down from the reflector giving a complete distribution of the light. If the lamp is burning in the vertical position all of the light goes out the sides and had to be reflected back down minimising the intensity being directed at the growing area.
  18. Q. What is a good application for the parabolic reflector?
    A. Parabolic reflectors distribute the light very evenly but are extremely inefficient in their use of light. They are excellent for a vegetative crop or for lots of seedlings or cuttings but are not very good for high yielding crops with high intensity demands.
  19. Q. Parabolic reflectors distribute the light very evenly but are extremely inefficient in their use of light. They are excellent for a vegetative crop or for lots of seedlings or cuttings but are not very good for high yielding crops with high intensity demands.
    A. Choose the flat white over semi gloss. It reflects better than the semi gloss. Glossy paint has light absorbing varnish that does not reflect as well as the flat white does.
  20. Q. What is a light mover? Are they beneficial to a grow room?
    A. A light mover is a mechanized device used to slowly move the grow lamps around to achieve maximum efficiency from your lamps. They come in the form of a 6 foot track which moves the lamp back and forth slowly, approximately every 10 minutes each way. Sun circles are designed to rotate the lamps in a slow circular motion above the growing area. These are both very beneficial to an indoor garden because you can bring the lamps closer to the plants without burning and the light can get at all angles of the plant saving the grower from constantly rotating the plants. Light mover are usually very efficient to operate and can really help with an increase in yield without the increase in lamps.
  21. Q. My ballast seems to operating at a high temperature, but how can I know if it's too hot?
    A. The best way to tell if your ballast is running too hot is to take a wooden kitchen match and touch to the ballast box. If it ignites the match then it is operating too hot. I would recommend having it looked at by a professional or have it serviced at your local hydro shop.
  22. Q. Does the heat coming off of my ballasts make a big difference in my grow room?
    A. Yes if heat is already a problem in your garden then I would suggest moving your ballasts outside the grow room. Especially if there is more than 1. They can really increase the overall room temperature.
  23. Q. What is the most efficient lamp to operate?
    A. The 600 watt HPS is the most efficient High Intensity Discharge lamp to operate to date. It has the highest lumen per watt ratio of any of the HID lamps on the market.
  24. Q. What is the best position to have my ballasts in?
    A. If the ballast is mounted in a protective housing (ballast box) then it should be kept up off the ground. Milk crates or cement blocks are excellent for this. Place a piece of heat resistant rubber under the box to reduce any vibrations the box may give off. They can sometimes really hum and that can get irritating. I suggest having all ballasts mounted in proper casings. Un- protected ballasts are usually trouble waiting to happen.
    Tips from MMAD Hydroponics:
    - 1) If at all possible keep your ballasts out of your grow room, this will help eliminate the un-needed heat source that will have to be looked after / exausted out of grow room.
    - 2) If a segregated ballast room is possible put your ballasts in that alternative location / room, if a ballast rack made of steel rods is accessable, use it as this will help disperse the heat away from ballasts..... put small fan pointing towards ballast rack and drop in an inline wall fan "5" or 6" wall fan" at a high location in your ballast room to flush the generated heat outdoors.. Find a good working Light layout design ideas for your grow room (Click here - scroll down page)


Lighting Glossary: Things you need to know about lighting.

WHAT IS?

AMPERE (AMP) - The unit used to measure the strength of an electric current.

ARC - The luminous discharge of electricity between two electrodes in HID lighting.

ARC DISCHARGE - A transfer of electricity across two electrodes (anode and cathode), characterized by high electrode current densities and a low voltage drop at the electrode.

ARC TUBE - The enclosure which contains the luminous gases and also houses the arc.

BALLAST - An auxiliary piece of equipment designed to start and to properly control the flow of power to gas discharge light sources such as fluorescent and high intensity discharge lamps. In metal halide systems, it is composed of the transformer, capacitor and connecting wiring; sodium systems require an igniter in addition to the transformer and capacitor.

BU - An industry code indicating that the bulb is to be operated only in a base up position.

BULB - The glass outer envelope component of an HID lamp which protects the arc tube.

BULB WALL TEMPERATURE - The temperature at the bulb wall of a lamp, which effects lumen output and input wattage and which is important in lighting calculations.

CANDELA (CD) - A unit of luminous intensity in a given direction, equal to one lumen per steradian.

CANDLEPOWER (CP) - The luminous intensity of a light source, as expressed in candelas.

CANDLEPOWER DISTRIBUTION CURVE - A curve that represents the varying distribution of luminous intensity of a lamp or luminaire.

CAPACITOR - An electronic device that can store electrical charge. The capacitor is one of the main components of an HID lighting ballast. Because they can store a very strong electrical charge, capacitors can be very dangerous to someone who is unaware of this fact and opens a ballast in order to examine or repair it. If one does not know how to safely discharge the stored electricity, one should allow a trained technician to do any ballast repairs.

COLD START TIME - The length of time required to bring an HID lamp to 90% light output from a cold condition.

COLOR TEMPERATURE or KELVIN TEMPERATURE - The unit of measurement to express the color (spectrum) of light emitted by a lamp; the absolute temperature of a blackbody radiator having a chromaticity equal to that of the light source (see correlated color temperature).

CONVERSION BULB - A bulb of a certain spectrum type (e.g. sodium) specially designed to operate while used in the fixture/ballast of a different type (e.g. metal halide). The most popular conversion bulbs by far are sodium conversion bulbs, which allow one to have the sodium spectrum while still using a metal halide system.

CORRELATED COLOR TEMPERATURE (CCT) - A specification of the color appearance of a light source, relating its color to that of a blackbody radiator, as measured in Kelvins (K). CCT is a general measure of a lamp's "coolness" or "warmness."

DOME - The portion of an HID outer bulb located opposite base (the neck and threads).

DOME SUPPORT - The spring-like brackets which mount the arc tube within the outer envelope (bulb).

DISCHARGE LAMP - A lamp that produces light by discharging an electric arc through a mixture of gases and gaseous metals.

ELECTRODES - Filaments located at either end of a discharge lamp that maintain an electrical arc between them. See arc discharge.

FIXTURE - The electrical fitting used to contain the electric components of a lighting system.

FLUORESCENT LAMP - A discharge lamp in which a phosphor coating transforms ultraviolet energy into visible light. Fluorescent lamps are good for starting seedlings and rooting cuttings, but do not have enough intensity to sustain aggressive growth in plants in the later stages of life, and are not efficient enough in their conversion of electrical power to lumens of light output.

FOOTCANDLE - A standard measurement of light intensity, representing the amount of illuminance on a surface one foot square on which there is a uniformly distributed flux of one lumen. More simply, one footcandle of illuminance is equal to the light emitted by one candle at a distance of one foot.

FREQUENCY - The number of waves or cycles of electromagnetic radiation per second, usually measured in Hertz (Hz).

HALOGEN LAMP - A short name for the tungsten-halogen lamp. Halogen lamps are high pressure incandescent lamps containing halogen gases such as iodine or bromine which allow the filaments to be operated at higher temperatures and higher efficacies. While excellent for home lighting and similar applications, halogen lamps are not effective or efficient as grow lights due to their limited spectrum and high operating temperatures.

HID - The popular acronym for High Intensity Discharge.

HIGH-INTENSITY DISCHARGE (HID) LAMP - A general term for mercury, metal halide and high-pressure sodium lamps. HID lamps contain compact arc tubes which enclose various gases and metal salts operating at relatively high pressures and temperatures.

HIGH-PRESSURE SODIUM LAMP - High-pressure sodium lamps operate by igniting sodium, mercury and xenon gases within a sealed ceramic arc tube. Sodium lamps emit light energy in the yellow/red/orange regions of the spectrum; the red spectrum stimulates flowering and fruit production. Many indoor gardeners switch to sodium lamps when it is time to induce flowering or fruiting of their plants.

HOOD - The reflective cover used in conjunction with an HID lamp. The more reflectivity a hood can provide, the more effective it is.

HOR - An industry code indicating that the bulb is to be operated in a horizontal position.

HOT SPOT - The area immediately under an HID lamp where the light intensity is strongest. Hot spots cause uneven growth, but can be remedied by using light movers.

HOT START TIME - The length of time required to bring an HID lamp to 90% light output after a short power interruption.

IGNITOR - A component of the ballast necessary for the starting of the bulb in sodium systems.

ILLUMINANCE - The density of incident luminous flux on a surface; illuminance is the standard metric for lighting levels, and is measured in lux (lx) or footcandles (fc).

ILLUMINATION - The act of illuminating or state of being illuminated. This term is often used incorrectly in place of the term illuminance to denote the density of luminous flux on a surface.

INCANDESCENT LAMP - A light source which generates light utilizing a thin filament wire (usually of tungsten) heated to white heat by an electric current passing through it. Incandescent lamps are the most familiar type of light source, with countless application in homes, stores and other commercial settings. Light is produced by passing electric current through a thin wire filament, usually made of tungsten. Incandescent lamps are totally ineffective as grow lights; they have very limited spectrum, are very inefficient in their conversion of electrical power to lumens of light output (lumen-to-watt ratio). They also put off far too much heat per watt to use in horticulture, even if the above-mentioned problems did not exist.

INTENSITY - A term referring to the magnitude of light energy per unit; light intensity diminishes evenly as you get further from the source.

KELVIN TEMPERATURE (K) - The unit of measurement to express the color (spectrum) of light emitted by a lamp; the absolute temperature of a blackbody radiator having a chromaticity equal to that of the light source (see correlated color temperature). A standard clear metal halide HID lamp has an average Kelvin temperature rating of 4,000K.

KILOWATT (kW) - A unit of electric power usage equal to 1,000 watts.

KILOWATT HOUR (kWh) - A measurement of electric energy. A kilowatt hour is equal to 1,000 watts of power used over a period of one hour.

LAMP - An electrically energized source of light, commonly called a bulb or tube.

LAMP LIFE - A measure of lamp performance, as measured in median hours of burning time under ANSI test conditions.

LAMP LUMEN DEPRECIATION (LLD) - The decrease over time of lamp lumen output, caused by bulb wall blackening, phosphor exhaustion, filament depreciation, and other factors.

LAMP STARTING - Generic term used to describe a discharge lamp's starting characteristics in terms of time to come to full output, flicker, etc.

LIGHT - Radiant energy which can be sensed or seen by the human eye. The term generally applied to the visible energy from a source. Light is usually measured in lumens or candlepower. When light strikes a surface, it is either absorbed, reflected or transmitted. Visible light is measured in lumens.

LIGHT MOVER - A motorized device which moves an HID lamp back and forth across the ceiling of a grow room to provide more even distribution of the light.

LUMEN - A measurement of light output; refers to the amount of light emitted by one candle that falls on one square foot of surface located at a distance of one foot from the candle.

LUMINAIRE - A complete lighting unit, consisting of a lamp or lamps together with the components required to distribute the light, position the lamps, and connect the lamps to a power supply. Often referred to as a "fixture."

LUX - A standard unit of illuminance. One lux is equal to one lumen per square meter.

METAL HALIDE LAMP - A high-intensity-discharge lamp in which the light is produced by arcing electricity through a mixture of metal halides. The light produced by metal halide lamps is in the white-blue spectrum, which encourages vegetative growth and "bushiness" while discouraging upward growth. This is the bulb to use in the first, vegetative phase of plant growth.

MERCURY VAPOR LAMPS - The oldest member of the HID family, mercury vapor lamps work by arcing electricity through mercury vapor. While more efficient than incandescent, halogen and fluorescent lamps, mercury vapor lamps have the least efficient lumen-to-watt ratio of the entire HID family. This, combined with an improper color spectrum for horticultural applications, makes mercury vapor lamps a poor choice for a grow light.

NECK - The narrow, tubular end of the HID bulb, attached to the threads.

PARABOLIC REFLECTOR - A lighting distribution control device that is designed to redirect the light from an HID lamp in a specific direction. In most applications, the parabolic device directs light down and away from the direct glare zone.

PHOTOPERIOD - The relative periods of light and dark periods within a 24-period. Also referred to as daylength.

PHOTOSYNTHESIS - The growth process by which plants build chemical compounds (carbohydrates) from light energy, water and CO2 (carbon dioxide).

PHOTOTROPISM - The gravitation of a plant part toward a light source.

REFLECTOR - The term sometimes used to refer to the reflective hood of an HID lamp.

REFLECTIVITY - The measure of the reflective quality of a surface; the relative ability of a given surface to reflect light away from it without absorbing, diffusing or otherwise compromising the light's quality, intensity and spectrum.

SOCKET - The threaded, wired receptacle that an HID bulb screws into.

SODIUM LAMP (HIGH-PRESSURE SODIUM LAMP) - High-pressure sodium lamps operate by igniting sodium, mercury and xenon gases within a sealed ceramic arc tube. Sodium lamps emit light energy in the yellow/red/orange regions of the spectrum; the red spectrum stimulates flowering and fruit production. Many indoor gardeners switch to sodium lamps when it is time to induce flowering or fruiting of their plants.

SON-AGRO - A sodium bulb which, according to the manufacturer, produces 30% more blue light than standard sodium bulbs. The 430-watt SON AGRO also emits 6% more light than the standard 400-watt sodium lamp.

SPECULAR REFLECTION - The redirection of incident light without diffusion at an angle that is equal to and in the same plane as the angle of incidence.

STERADIAN - A unit solid angle on the surface of a sphere equal to the square of the sphere's radius.

TRANSFORMER - The component in the ballast that transforms electric current from one voltage to another.

U (for UNIVERSAL) - An industry code indicating that the bulb can be operated in any position: horizontal, vertical (base up) or any other.

ULTRAVIOLET (UV) LIGHT - Light with very short wavelengths, out of the visible spectrum.

UNDERWRITERS LABORATORIES (UL) - A private organization which tests and lists electrical (and other) equipment for electrical and fire safety according to recognized UL and other standards. A UL listing is not an indication of overall performance.

WATT (W) - A unit used to measure electric power. One watt equals one joule/second.

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