Frequently asked Questions

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What is Hydroponics?
Hydroponics is growing plants without soil. Plants are usually grown in mediums that have no nutrient value of their own (inert), and the nutrients are supplied with the water. Examples of mediums would be clay pellets (hydroton), or rock wool (looks a lot like insulation rock wool, but is agricultural grade) or even just suspended above the nutrient & water mix by a neoprene plug. ^ top
What are the Benefits of Hydroponics vs. Soil?
  • No more messy or bulky bags of soil/soil less mix.
  • No more Transplant shock. In Hydroponics the size of the pot doesn't determine how big the plant will be. You can have a 6 ft tall plant in a 6 in basket in a drip system.
  • Larger plant with a small root mass when compared to a plant the same size grown in soil. General rule of thumb for soil grown plants is 1 gallon for each foot in height, so a 7 ft tall plant should really have a 7 gallon pot.

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What Can I Grow?
You can grow anything hydroponically that can be grown in soil. Some things like root vegetables are a bit more complicated and fruiting plants like tomatoes need to be pollinated to set fruit. Outside bees and other insects do this, inside you will need to do it. This is simply a matter of using a small brush or something similar to move pollen from one flower to another.^ top
Quick Reference Conversions
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Why use supplemental lighting for indoor or greenhouse gardening?
  • To extend the growing period in your greenhouse. By extending the 'day length' with supplemental lighting, you greatly enhance your growing success.
  • To provide light in areas, basement for example, that don't get any natural light.
  • From stronger, healthier seed starts, into faster maturing more vigorous plants that offer higher yields of fruits and flowers, than can be achieved without supplemental lights.
  • It is very energy efficient and the cost of operating one of these systems is comparable to using one of your kitchen appliances.
  • Significantly increase health, strength growth rate and yield of your plants.
  • Plants that were purchased for outdoor patios and decks can be moved indoors for the winter under H.I.D. or high output florescent lights allowing them to thrive year round.

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What are Other types of supplemental lighting?
Traditional tube fluorescents:
Approximately 30 lumens/watts. Doesn't produce light for the first and last 2 inches approximately. Provide light to an area 8 to 10 inches below the light. These fixtures are excellent for starting seeds and cuttings. Put out very little heat, and so are kept close to plants.
T5 fluorescent fixtures:
These fixtures are excellent for starting seeds and cuttings. Put out very little heat, and so are kept close to plants. Slim design enables better photo-optic control of emitted light (produces light from one end to the other). Use less raw materials, and components for manufacturing. Reduced packaging for lamp and fixture due to relative size.
T5's are constructed using 40% less glass; contain 30% less phosphor and 70% less mercury then traditional tube fluorescents. Longer lamp life means reduced maintenance cost and less going to landfills. Very little wasted light energy in terms of plant growth. Photosynthesis rate peaks at 435nm and 680nm.
High wattage self ballasted fluorescents:
Available in higher wattage, up to 200 watts. Can have mogul or standard base. Covers a larger grow area, in comparison to other fluorescents. Produce less heat then H.I.D. fixtures.
Incandescent lamps, halogen or standard household bulbs:
Approximately 15 lumens/watts. Very inefficient use of power. Not used by serious gardeners because it produces the wrong spectrum of light and is not cost effective. Incandescent light is assumed to have a CRI of around 100, so will render all colors correctly.
High Intensity Discharge (H.I.D) light systems:
System consists of ballast, reflector, socket and a lamp (light bulb). The ballast is the driving force that converts the energy and illuminates the lamp. H.I.D options include Mercury Vapor, Low Pressure Sodium, and the ones listed below are most commonly used by serious gardeners.
  • Metal Halide Ballast :
    Available in various sizes to cover a wide variety of garden sizes. Very high in blue spectrum, this is better for vegetative growth because it keeps the distance between leaf axis (internodes) shorter. Ballast and bulb must be the same wattage to work properly, and the same type (metal halide ballast, metal halide bulb). Conversion bulbs are available; this is a High Pressure Sodium bulb that will run on metal halide ballast. With this conversion bulb you lose a bit of light output to the igniter that is built into the bulb, so 400 watt metal halide ballast will light a 360 watt conversion bulb.Bulb should be replaced yearly to maintain optimum growth. MH has a CRI of about 70, so renders 70% of colors correctly.
  • High Pressure Sodium Ballast :
    Available in various sizes also. Very high in red/orange spectrum. This is better for fruiting and flowering plants. It is also a pretty good multi-purpose light as well. In vegetative stage internodes will be slightly elongated compared to plant under Metal halide system. Conversion bulbs are also available for this system, but unlike the other one you don't lose any of your light output. 400 watt High pressure sodium will convert to 400 watt metal halide. Bulbs should be replaced every 2 years to maintain growth, and yearly for aggressive growth. HPS has a CRI of 22.

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Light Output Comparison Chart
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Which light is right for you?
Typically gardeners will provide at least 25 watts per square foot of garden space. You may need less if this is supplemental, or the plants being grown don't require as much light. Some gardeners prefer to use more then this amount to achieve faster growth rates. There's really no such thing as to much light. But if you have a small enclosed area with a lot of light, you most likely will have problems controlling the heat in this space. Lights are usually run for 12 to 18 hours with a dark cycle of 6 to 12 hours. Type of light varies, and this is entirely up to you and what the requirements are for the plants you are growing. I usually suggest getting a high pressure sodium if the plants tend to have a longer flower cycle, and metal halide if it is strictly a vegetative plant (never flowers). Coverage area varies depending on if this is your only light source. If this is supplemental lighting then it's as listed in the chart, as primary light source it maybe a slightly smaller area.^ top
What is the difference between HID and Fluorescent lighting with regards to plant growth?
Traditionally, fluorescent lighting is used for seedling, cuttings, and plants with low light requirements. HID was used for established plants, and plants with higher light level needs. Advancements in Fluorescent lighting technology has led to more options. T5 fluorescent lighting is the latest in plant growth lighting. Their high light output, combined with its low heat and energy consumption make it an ideal light source for a broader selection of plants. ^ top
What are the major differences between HID ballast and electronic ballast?
Frequency output to the lamp and energy conversion from electricity to usable light are the biggest differences between HID ballast and electronic ballasts. HID ballast produces a frequency of 60Hz. Electronic ballasts vary from manufacturer to manufacturer, but the frequency produced can be 400x that of an HID Ballast. HID ballast produce more heat than electronic ballast, thus making electronic ballasts more energy efficient. You're not likely, however, to save money on your electric bill by using electronic ballast. HID ballast have been around over 60 years, while electronic ballast (esp. 400watt and higher) is relatively new technology. ^ top
Are electronic ballasts more energy efficient?
Electronic ballasts are more efficient at converting electricity into usable light. Since your power bill is based on kilowatt-hours and not efficiency, 1000 watt electronic ballast will cost you about the same as a 1000 watt HID ballast to operate. ^ top
How much energy will my light use?
An average system will increase your electricity cost about $8 to $20 per month. The exact amount depends on the wattage of the system and the number of hours operated. Check out the quick reference further down the page. ^ top
Do I need special wiring in my house for my lighting system?
Lighting systems are available in a variety of voltages. The standard used by most gardeners is 120volts/60Hz which plugs into a standard wall outlet. Other voltages may require special circuits and receptacles. Always contact a licensed electrician if the light you purchased has special voltage requirements and never exceed more then 75% of the rated ability of the fuse/breaker. Other voltages available are 120v, 208v, 240v, 277v, and 480v - all at 60Hz. Fluorescent lighting varies, but most re from 100v to 277v and 50Hz or 60Hz. ^ top
Will I save on my electricity bill if I run my system with 240volts?
No. Electric companies base your bill on Wattage, not Voltage or Current. While ballasts wired 240volt will draw less current and run a little cooler then one wired 120 volt, it will not save you any money on your electricity bill. ^ top
How often do I need to change my lamp/bulb?
Most lamp manufacturers rate their lamps by "Average Life Hours" and usually claim 10,000 to 24,000 hours. These ratings are based on when the lamp will completely fail to come on. They do not factor in loss of color. HID lamps lose intensity and color spectrum through normal use. This is ok if you're lighting a warehouse, but when it comes to plant growth, these losses can mean wasted electricity and poor plant performance. We usually recommend that you replace a metal halide bulb after running it for a year, and 2 years for high pressure sodium. ^ top
How long should I run my lights?
This depends on the type of plant, and if there is any natural sunlight. But generally during the vegetative stage of growth 14 to 18 hours of light. If you are actively flowering or fruiting plants the rule is to run your lights 12 hours a day if you have no natural light. ^ top
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How high do I need to hang my lights above my plants?
When mounting your lighting fixture, you want to keep it close to the plants without burning the plants. Simple rule is "if it is comfortable for the back of your hand, it will be a safe distance for your plants." With fast growing plants, you may need to check the height on a regular basis as the plants that get too close to the lamp will be severely burned. I suggest using light gage chain; this makes it easy to adjust as needed. You can use many different kinds of air-cooled reflectors which will allow the lights to be that much closer to your plants. All artificial light diminishes rapidly as it moves away from the source at a rate of 1/distance squared. For Example; 1ft = 1000 FC (foot candles), 2ft = 250 FC, 3ft = 111 FC. ^ top
Typical mounting heights diagram
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How big of an area will my light cover?
The size of the garden area will determine the wattage you need. If this is the only source of light, a 1000watt will cover roughly 7x 7; this would be the primary growing area. Plants placed outside the primary growing area, will stretch and bend toward the light. This is called phototropism. When using multiple light fixtures the best results are achieved when the area of coverage overlap. ^ top
HID average coverage area by wattage diagram
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Can I run a 1000 watt bulb in a 400 watt system?
No! The internal components of the ballast are designed to send the correct voltage and current to the lamp. Mixing lamp, and ballasts will result in the premature failure and will void the manufacturer's warranty. Consider the size of your garden area prior to making a light purchase. It is better to grow into a fixture then out of one. ^ top
Can I run a 430 bulb in a 400 watt system?
Yes, the internal components of both ballasts are almost identical. You will only get 400 watts of light of the lamp, however. Some bulbs will also quit working sooner then expected. ^ top
Why can't I put a metal halide bulb into a high pressure sodium ballast or vice versa?
The internal components of the two systems are different, as are the gases in the arc tubes of the two lamps. Metal halide ballast has a core and a capacitor, while high pressure sodium has a core, capacitor and igniter and operates at a different output frequency. You can get conversion bulbs. ^ top
What is a conversion bulb?
It's a lamp that operates on the opposite ballast it was designed for. For example, a 940watt conversion lamp is a high pressure sodium lamp. This lamp operates on metal halide ballast, because the igniter is built into the bulb and accounts for the 60 watt loss of light. If you have high pressure sodium ballast, and convert to metal halide lamp, you don't lose any light output. ^ top
Light required for photosynthesis is:
Referred to as PAR (Photosynthetically Active Radiation) contains the wavelengths between 400 and 700 nanometers. Falls just within the so-called visible spectrum (380-770nm). Plants use the blue to red light as their energy source for photosynthesis. ^ top
What is Color Rendering Index (CRI), Color Temperature (K) and Lumens?
CRI is a subjective measurement of how well a lamp source renders color. It's a measurement of the degree of color shift an object undergoes when illuminated by a light source when compared to a reference source of comparable color temperature. Color temperature refers to the relative whiteness of a piece o tungsten steel heated to that temperature in degrees Kelvin. HPS has a warm (red) color temperature of around 2700k as compared to MH at 4200k, which has Lumen is a measurement of light output. It 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. Traditionally, lumens have been the benchmark for a lights ability to grow plants; meaning better lights, better plants. However, recent studies have shown that broader color spectrum in the lamp will perform better then a light with high lumen output, especially when it comes to plant growth. ^ top
Photosynthetic activity range
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