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OverGrowFAQ-HID lighting

in Lighting Mon Nov 25, 2013 1:19 am
by ozzydiodude • The Weird One | 2.413 Posts | 11222 Points

H.I.D Light description

High-pressure sodium lamps contain an internal arc tube made of a translucent ceramic material (a form of aluminium oxide known as "polycrystalline alumina"). Glass and quartz cannot be used since they cannot maintain structural strength at the high temperatures (up to 1300 degrees C) encountered here, and hot sodium chemically attacks quartz and glass. Like other HID lamps, the arc tube is enclosed in an outer glass envelope. A small amount of metallic (solid) sodium in addition to mercury is sealed in a xenon gas fill inside the ceramic arc tube. Some versions of this lamp use a neon-argon mixture instead of xenon. Basic operation is otherwise similar to metal halide or mercury lamps. High-pressure sodium lamps produce an orange-white light and have a luminous efficiency much higher than mercury vapour or metal halide lamps. Metal halide lamps are constructed along similar lines to mercury vapour lamps. However, in addition to the mercury and argon, various metal halides are included in the gas fill. The most popular combination is sodium iodide and scandium iodide. A few versions of this lamp have lithium iodide as well. A much less common version has sodium iodide, thallium iodide, and indium iodide. The use of these compounds increases the luminous efficiency and results in a more pleasing color balance than the raw arc of the mercury vapour lamp. Thus, no phosphor is needed to produce a color approaching similar to that of a cool white fluorescent lamp with more green and yellow than a mercury vapour lamp (without correction). Some metal halide lamps have a phosphor that adds some orange-ish red light, but not much, since the metal halide arc does not emit much UV. High-pressure mercury vapour lamps contain an internal arc tube made of quartz enclosed in an outer glass envelope. A small amount of metallic (liquid) mercury is sealed in an argon gas fill inside the quartz tube. After the warm-up period, the arc emits both visible and invisible (UV) light. High-pressure mercury vapour lamps (without color correction) produce a blue-white light directly from their discharge arc. Phosphors similar to those used for fluorescent lamps can be used to give these a color closer to natural light. (Without this color correction, people tend to look like cadavers). Mercury vapour lamps have the longest life of this class of bulbs - 10,000 to 24,000 hours. The technology was first introduced in 1934 and was the first of the commercially viable HID lamps.

HID lighting
is generally accepted as a better light for growing cannabis for a few reasons...
· It has much better light penetration
· It is much more powerful (higher lumen output)
· It is stronger in light spectrums suited for growing plants What can we do to combat these problems to make the most out of our fluoro’s?
· Use a good reflector. Desk lamp reflectors are perfect, along with coke cans (cut in half from top to bottom).
· Purchase lights with high energy saving capabilities (e.g. high watt ratings)to increase light penetration
· Purchase lights with suitable spectrum strengths for each phase of growing (eg warm white, cool white etc.)
· Keep the lights close to maximize intensity
NOTES: For good results, these lights must be used with a good quality reflector. They give of 360 degrees of light (in a 2D cross-section) but you will only really need 90 degrees of light (maximum). Building a reflector will help concentrate all the light to the area needed, instead of wasting it lighting up the ceiling of your grow room! Although you can successfully grow and flower a cannabis plant under a fluorescent, your results will be poor and you will most likely be disappointed. Use these lights only for seedlings and clones, and perhaps the vegetative stage of the cycle. A HID light is recommended for flowering.


Does the bulb have to match my ballast?

Yes Ballasts and Bulbs Should be Matched. HID bulbs generally need specific ballasts, and any given ballast can usually safely and effectively operate only one type or a few types of HID bulbs. The bulb wattage must be matched to the ballast. A smaller bulb will usually be fed a wattage close to what the proper bulb takes, and will generally overheat and may catastrophically fail. Any catastrophic failures may not necessarily happen quickly. A larger bulb will be underpowered, and will operate at reduced efficiency and may have a shortened lifetime. The ballast may also overheat from prolonged operation with an oversized bulb that fails to warm. Even if the ballast and bulb wattages match, substitutions can be limited by various factors including but not limited to different operating voltages for different bulbs. Examples are: Pulse-start sodium lamps often have a slightly lower operating voltage than metal halide and mercury lamps of the same wattage, and ballasts for these sodium bulbs provide slightly more current than mercury and metal halide ballasts for the same wattage would. The higher current provided by the pulse-start sodium ballast can overheat mercury and metal halide lamps. Mercury and metal halide lamps may also "cycle" on and off in lower voltage sodium ballasts, such as many 50 to 100 watt ones. Metal halide lamps have an operating voltage close to that of mercury lamps in many wattages, but have stricter tolerances for wattage and current waveform. Metal halides also usually need a higher starting voltage. Most metal halide lamps 100 watts or smaller require a high voltage starting pulse around or even over 1,000 volts. 175 to 400 watt metal halide lamp ballasts can power mercury lamps of the same wattage, but the reverse is not recommended. Mercury lamps 50 to 100 watts will work on metal halide ballasts, but hot re-striking of mercury lamps 100 watts or smaller on metal halide lamps may be hard on the mercury lamp since the starting pulse can force current through cold electrodes and the starting resistor inside the mercury lamp. 1,000 watt mercury lamps come in two operating voltages, one of which is OK for 1,000 watt metal halide ballasts. A few wattages of pulse-start sodium (150 watts?) come in two voltages. A low voltage lamp in a high voltage ballast will be underpowered, resulting in reduced efficiency, possible reduced lamp life, and possible ballast overheating. A high voltage lamp in a low voltage ballast will usually cycle on and off, operate erratically, or possibly overheat. This will usually result in greatly reduced lamp life in any case. One class of sodium lamps is made to work in mercury fixtures, but these only work properly with some mercury ballasts, namely: 'Reactor' (plain inductor) ballasts on 230 to 277 volt lines. 'High leakage reactance autotransformer' ballasts, preferably with an open circuit voltage around 230 to 277 volts. NOT 'lead', 'lead-peak' nor any metal halide ballast! These sodium lamps may suffer poor power regulation and accelerated aging in the wrong mercury ballasts, especially after some normal aging changes their electrical characteristics. Also, these lamps may overheat and will probably have shortened life with pulse-start sodium ballasts. Many sodium lamps require a high voltage starting pulse provided only by ballasts made to power such lamps. To prevent dangerous accidents please keep remote ballasts away from tap points and on an elevated position (approx 5 inches off the floor) using a block or shelf.

What is a conversion bulb?

A Conversion bulb offers you the opportunity to switch the bulb in your Halide or Sodium fixture without changing ballasts. Many cannabis gardeners prefer Halide light for vegetative growth and a Sodium light during blooming but a separate fixture is normally required. A Conversion bulb is a convenient option when you only have room for a single fixture but want the advantage of both Sodium and Halide lighting. Please note: High intensity discharge conversion bulbs are system specific. Sodium conversion bulbs are designed to be used in metal halide or mercury vapour fixtures only. Halide conversion bulbs are designed to be used in high pressure sodium fixtures only.

When should I replace my lamp?

It depends on what type of lamp you're using. These recommendations are based on 18 hours of daily use. Type When to replace 1000w (mh) lamps 12 months 1000w (mh) lamps "agro sun & warm deluxe 15 months 1000w (mh) lamps u cool deluxe 6500k 12 months 400w (mh) lamps 18 months 400w (mh) lamps u cool deluxe 6500k 15 months <br>250w (mh) lamps u cool deluxe 5400k 12 months 175w (mh) lamps daylight bulb 5500k 15 months All regular 75w to 250w (mh) lamps 15 months Replace all hps after 24 months, with the exception of the son agro and super agro, replace after 15 months. Fluorescents should be replaced every 15 months. After 12 months, check the tubes if running more than one tube on a single ballast. Always replace all fluorescent tubes at the same time. Remember to always write down the day that you start using a new HID lamp. This will allow you to calculate when to replace it for best results

Where can I buy MH/HPS lights?

Look in the Yellow pages for an Electrical Supplier/Wholesaler in your area. Call them up they should have these lights in all wattage’s in stock. Their prices will be half that of a Hydro stores. Pay in cash.


How much will it cost to run my light?

Depending on where you live the average cost of running a 1K light 12/12 is about $20-$30 a month in electricity.

What is a switchable ballast?

A switchable ballast allows you to run a standard halide or sodium bulb from one ballast, you just insert the appropriate lamp and set the switch to the correct operating setting. This type of ballast enables growers to bypass costly conversion lamps and maintain the higher light output from non conversion bulbs.

What type of timer should I use for my H.I.D light?

You should use a 15 amp heavy duty timer. If you use a standard timer to switch your H.I.D ballast it may malfunction, as the incorporated electronics are not designed to switch such inductive loads. Standard timers are only designed to switch resistive loads up to 3kw, for example, fans and pumps. To avoid unwanted stress such as hermies, or even a fire, make sure you buy the correct timer.

Bulb information and specifications (incomplete)
Below are some tables compiled from data about various lamps so that you can compare and contrast different lamps yourself. Things to remember! Different sources of light have different light spectrums some better for plant growth and some not so good such as incandescent bulbs. Plant growth is heavily influenced by the amount and colour of the available light. Blue light at about 450nm favours root growth and intense photosynthesis. Red colours at 600 to 700nm stimulate rapid stem growth, intense flowing and chlorophyll production. An interesting note about PAR watts and lumens for MH and HPS lamps is that the correlation between the two is over 97%. Meaning that for HPS and MH lights (remember the very restricted sample used here) on average there is less than 3% variance when estimating PAR watts from lumens. But remember that is an average and some lamps the difference may be much more.

Metal Halide safety and fixture recommendations

HPS (High Pressure Sodium) lamps can burn in any orientation. MH (Metal Halide) lamps come in three basic types: *Base up (BU), which must be operated in the base up position. *Horizontal (HOR), must be operated in the horizontal position. *Universal (U), which may be operated in any position. Orienting metal halide lamps in burning positions other than those specified can result in severe reductions in performance and potential nonpassive failure. Lamp life,light output and color can be affected by the burningposition. Some burning positions may need enclosed fixtures for safety reasons. When replacing ANY HID (High intensity Discharge) lamp, never touch the bulb with bare hands. HID lighting gets exceptionally hot and any oils from your skin left on the bulb will burn and can cause the lamp to burst. Always use soft, clean gloves when handling the lamps. Observe extreme caution while foliar feeding any plants around exposed lamps. I suggest turning off any fans and ventilation while spraying the plants, any water blown onto an exposed, burning lamp can cause it to explode in your face. Be safe.


Let's help each other, by spreading our knowledge of the plants we love
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