Lights two Goose Gardens Gardening Supplies

Here is yet much more detail on flourescent lights

Fluorescent tubes seem so similar that it is easy to assume they are more alike than they really are. Fluorescent tubes use high voltage electricity. The fixture "ballast" is used to convert regular house old electricity into the high voltage that is required. The tubes themselves are coated on the inside with chemicals called "phosphors." These glow and give off light in response to the high voltage electricity.

It happens that our eyes are very adaptable for different sorts of light, so we tend not to be so very aware of changes in light. You can see this by wearing colored sunglasses. Very soon, you will see the world around you as "normal" despite the obvious effect of the colored lenses.

There are now a whole variety of different phosphors that can be used inside a light tube. Each different phosphor gives off a different color profile. If you were to use only one phosphor, you would likely have a very weird looking light as a result.

Each manufacturer has their own "recipe." These days, each manufacturer offers several different types of bulbs with different phosphor recipes designed to give off different sorts of light. As a result, cool white bulbs from different manufacturers are only similar, but not the same. A better and more expensive tube will often be made with more and better phosphors to achieve a more pleasant and balanced light. A cheaper tube might be manufactured with fewer and less expensive phosphors- its light might be functional for situations like stores or offices where people may be less picky.

The very old cool white tubes that people bought had primitive phosphors. The light they give off is highly biased towards the color green. It is not a flattering color for skin and faces. Many of the newer cool white bulbs are still biased towards blue green light, but have a better color balance than the worst cool white tubes of old. But in any case, it is well to remember that you might not be doing yourself a favor by getting the very cheapest no-name bulb you can find. Note-I have just read that cheaper bulbs tend to wear out quicker…. And it could make sense, but I do not know this for sure.Our local home depot store has a whole variety of bulbs lighted side by side so you can actually see the difference in brightness and color.

Light color (temperature of light source). Our eyes (and of course the eyes of our fish and our plants' photosynthesizing elements) are "calibrated" to perform in ambient sunlight. Subsequently, our eyes interpret this light as white light. As all of us know, "white" light simply doesn't exist. In simple words, "white" is not a color but a combination of many wavelengths (colors), which form a spectrum

Light Source

Temperature (degrees Kelvin)

Candle flame

1800°

Incandescent lamps

from 2500° to 3050°

Fluorescent warm white lamps

3000°

Fluorescent cool white lamps

4100°

Daylight

6500°

Midday sunlight

North Sky light

5500°

7500^o

Cloudy sky

7000°

Clear sky

from 10000° to 30000°

Kelvin is a temperature scale that is used in the scientific community. 100 degrees Kelvin is boiling water, 0 degrees kelvin is freezing water We all know that hot metal can glow red….A normal incandescent light bulb uses a very hot metal thread to generate light. The reference to "Kelvin" is supposed to refer to the color of light that would be emitted by a lump of iron heated to various different temperatures. Ranging from red hot… to the white-hot temperatures of the sun.

Color Name

Warm White

Cool White

Daylight

Typical Color Temperature (in Kelvin's) or approximate Wavelength (in Nanometers)

3,000K
to
3,500K

4,100K
to
4,200K

6,000K
to
7,000K

Phosphor wavelengths commonly used in lamps

At least one phosphor from each of the Red, Green and Blue columns is used. The ratio of the phosphors used determines whether the produced light is perceived as Warm White, Cool White, or Daylight shades.

Light (visible)

Visible light is that part of the electro-magnetic spectrum that lies between the wavelengths of ultraviolet (380 nm) and infrared (700 nm).

Light (invisible)

This consists of wavelengths which are not "seen" by the human eye. Of course, this doesn't mean that the rest of the animals are not able to see in those regions. The most known regions are the infrared and the ultra violet ones, which happen to be below the red and over the violet rays respectively. The UV rays are useful in sterilizing the water.

Watts

This is an indication of the power consumption required by the lighting equipment you use. Two light sources requiring the same power may produce different levels of light. Usually the energy, which is not used to produce light, is released in the form of heat. For the aquarium purposes, heat is undesirable so the hobbyist should opt for those solutions that produce more light / watt consumed. Fluorescent tubes and Metal halide lamps make good use of electricity power, while incandescent and halogen lamps do not.

Lumens

This is the total amount of light a bulb is capable of generating and is perhaps the most important information you need to know from the manufacturer. If we have two light sources emitting in the same spectrum then the one, which emits more lumens, will be definitely brighter. However, for the aquarium hobbyist this is not absolute. A lamp may produce many lumens but be poorly focused (which means those lumens will never reach your plants or corals) or emit the wrong wavelengths or bands (green band for instance, instead of the red / blue you need).

Lux

This is the actual intensity of the light falling on a specified area and is defined as lumens per square meter. Which means that, if all the light from a 3000 lumen lamp was perfectly focused on a 1 square meter area, the light intensity at any spot would be 3000 lux. It is obvious that this is a much better way to express the lighting requirements. However, the amount of light that falls on your gravel or on the leaves of a specific plant in your tank is something you will have to measure. The manufacturer doesn't know the depth of your tank, the presence of reflectors etc. so he can't give you this figure. The difference between the Lumens and Lux is that Lumens are emitted while the Lux are Lumens that reach a specific surface.

CRI (Color Rendering Index)

The color rendering index identifies the degree of color shift objects undergo when illuminated by a particular light source. In simpler terms, the CRI expresses the degree to which a light source renders the true color impression. The CRI is an index and ranges from 0 to 100. A light source having a CRI of 100 means objects illuminated by it look like they're supposed to; that is their natural color is not distorted. A light source having a very low CRI would tend to make objects appear to be a different shade or even colour that they really are. An example of light with a high CRI is, obviously, sunlight. Some fluorescent tubes have a very high CRI (upper 80s or low 90s).

Kelvin temperature (Light color)

White light can have different "warmth". A bit more red/yellow and white light appears "warmer". A bit more blue and light appears "cool". This can be quantitatively assessed by assigning a color temperature, given in degrees Kelvin. Think of color temperature as the color of a block or iron (a black body) as it is heated to various high temperatures. A warm, reddish light is around 3500 degrees Kelvin, and above 6000 degrees Kelvin the light takes on a bluish tone. Sunlight is somewhere around 5000 degrees Kelvin. Which means that from the physicist's point of view, blue is "hotter" than "red". The "zero" in the Kelvin scale is the "absolute" zero which is a theoretical value (can't be reached). A body, which is brought to this temperature, is assumed to emit no radiation at all.

Spectrum

This describes the wavelengths of light that make up the light source. Visible light (see Glossary) is a continuous band of colors ranging from violet to red (380 - 700 nm). Sunlight and incandescent light is composed of all visible wavelengths. Fluorescent and metal halide bulbs emit only a few wavelengths (or bands) depending on the phosphors or rare earths they contain.

Light as an electromagnetic wave

Light is something strange. In physics it can be interpreted as both a particle (named a "photon") or a wave. Thus, it has the properties of both a particle (can fall on something, change course, will bounce off an obstacle etc.) and a wave (has a wavelength, period, frequency etc.). The wave "form" of the light is the most interesting one. Thus, the wavelength it the length between two peaks of the light wave (like the waves in the sea) while the frequency is how many such waves are sent per second. Light will travel 300.000 Km / second, no matter what its wavelength is. This means, that if it is short, more waves will be sent in a second, while if it is a long one, less waves will pass in a second. Thus, the longer the wavelength (red) the lower the frequency. The shorter the wavelength (violet) the higher the frequency. The energy, which is "carried" by a photon, is proportional to its frequency. As a result, the violet rays carry more than double the energy the red ones carry. This is of outmost importance for the photosynthesis of the plants and corals since they need the high-energy photons.

Loss of intensity

As we move away from the light source, the intensity of light drops geometrically. Thus, at double the distance only one fourth of the light intensity is available.

Ballast
Fluorescent lights require high voltage electricity to work. They use a device called a "ballast" to change regular house old electricity into the required high voltage. Older style ballasts are simple transformers… which mans that there are coils of wire around iron centers. These older style ballasts are still used most inexpensive light fixtures today. They need to use the older (style thicker) t 12 tubes. They are about 30 % less efficient than the newer ballasts. The bulbs burn out more quickly, and the bulbs tend to flicker, Also, you can get an annoying humming sound coming from the fixture. They also generate excess heat.

The newer ballasts are called electronic ballasts. They use solid state electronics to generate the high voltage. They are more efficient, quiet, the light tubes last longer, have no flicker, the tubes have a better color rendering ability, and the ballast generates much less excess heat. The fixture package may not specify the type of ballast… but if they say they are good for cold weather…. They are most likely the electronic ballast. All in all it is much better to spend a few extra dollars to get an electronic ballast fixture.

Photosynthesis
Photosynthesis is the operation of the plants in which light is used as the energy source to produce food (sugars). During this process, plants consume Carbon dioxide and release Oxygen while they "store" the light energy in the sugar molecules. This phenomenon can be visible in planted aquaria, ponds and lagoons, after some hours of lighting, in the shape of tiny bubbles coming out from little pores on the plants' leaves. The reaction is reversed in the dark. In the dark the plant will produce carbon dioxide and consume oxygen thus utilizing the energy which was stored in the sugars.