How much light for a 75gallon?
- Thread starter ilikeeels
- Start date
wangotango
Active Member
if all you want are softies, and most of the lps without getting into sps you could probably get away with the current orbit 4x 65w power compact fixture.
-Justin
-Justin
D
dacironi
Guest
of the specimens kept in a reef tank, other than fish or mobile invertebrates, are photosynthetic. That is, they receive part or all of their nutritional requirements from the lighting that they receive. This is accomplished by the fact that they have symbiotic algae which lives within the tissues of their bodies. The algae utilize the light for photosynthesis and the coral benefits from the byproducts of this process. If insufficient lighting is provided, the algae will die or slow down their activities and these animals will slowly starve to death. Also, some of the colors of photosynthetic corals and clams are attributed to the symbiotic algae and the coloration a specimen will often increase under higher intensity lighting.
Lighting is probably the biggest decision in setting up a reef tank. You can skimp on virtually everything else, but not this one unless you are willing to limit the inhabitants of your reef to those which can tolerate the lower quality light that you can provide. Like the size of your tank, your budget may determine for you the quality of light that you can give your reef. You cannot just walk into a pet store and buy that nice looking aquarium and expect the fluorescent hood that comes with it to work for your reef tank because it won’t.
Lighting has two important characteristics that you must consider, intensity and color. Intensity is the brightness of the light and relates to how much energy the lighting is putting into the tank environment. Color of the light is also important as the photosynthetic processes that are occurring in the tank are targeted to work optimally with the color of the light normally available on the reef.
Lighting Intensity
Intensity of the light relates to how much light energy is present at the surface of the water. There are a number of ways of calculating the amount of light you have or need in your tank, which are described below.
One of the more popular units of measure being used in literature now is the PAR (Photosynthetically Available Radiation). PAR relates to the amount of energy provided in the spectrum that is useful for photosynthesis. Unfortunately, there is no easy way for the hobbyist to directly measure PAR. This rating is most commonly used to compare the efficiency of one lamp to another.
The best way to actually measure the amount of light is to use a light meter made for this purpose. This type of meter measures lighting intensity in a unit of measure called Lux. A light meter will cost around $100 dollars. In general, the goal is to achieve a minimum of approximately 25,000 Lux at the surface of the water if keeping SPS corals with 20,000 to 40,000 being typical. Lower light tanks can get away with less. Measuring the light intensity using a light meter gives a completely accurate indication of how much light is really reaching your tank, however it is not really necessary.
One way to ballpark your lighting requirement is to use a watts-per-gallon calculation. This method is not as popular as it use to be since it does not take some variables into consideration such as tank depth or the efficiency of the light source, but it is still useful. You obtain this number by dividing the watts of lighting in your light fixture by the gallons of capacity in your tank. For a high light intensity tank, you should use a figure of 8-10 watts/gallon as your basic target. A lower light tank can get by with approximately 3-6 watts/gallon.. How does this compare with the typical lighting supplied by a tank manufacturer? As an example, a 55 gallon tank with one 4-foot long 40 watt fluorescent light which is a typical store bought configuration would have a watts per gallon of 40W x 1 bulbs = 40W total / 55 gallons = 0.75 watts per gallon! Now consider that you should aim for approximately 8 watts per gallon in your reef tank. For this 55 gallon tank, you would need about 55 gallon x 8 watts/gallon = 440W! That is about 11 times the amount of light provided by the store bought hood! Since it is physically impossible to put 11 40watt tubes above a 55 gal tank, it should be obvious that we need to find more efficient lighting schemes for our tank. If a low light tank is the target, you can see that the absolute minimum to achieve 3 watts/gallon would be 40W x 4 bulbs = 160W total / 55 gal = approximately 3 watts per gallon.
A better approach, especially when dealing with Metal Halide lamps is to size the lamps by the depth of the tank and determine the number of lamps by the square footage of the tank surface.
175W MH is suitable for up to 18” deep tank
250W MH for 18” to 24” deep
400W MH for anything deeper than about 24”
.
The other factor is the number of lights and the rule of thumb is that a MH lamp will illuminate approximately a 2’ x 2’ area of the tank. A 4-foot long tank would require 2 MH lamps.
Lighting is probably the biggest decision in setting up a reef tank. You can skimp on virtually everything else, but not this one unless you are willing to limit the inhabitants of your reef to those which can tolerate the lower quality light that you can provide. Like the size of your tank, your budget may determine for you the quality of light that you can give your reef. You cannot just walk into a pet store and buy that nice looking aquarium and expect the fluorescent hood that comes with it to work for your reef tank because it won’t.
Lighting has two important characteristics that you must consider, intensity and color. Intensity is the brightness of the light and relates to how much energy the lighting is putting into the tank environment. Color of the light is also important as the photosynthetic processes that are occurring in the tank are targeted to work optimally with the color of the light normally available on the reef.
Lighting Intensity
Intensity of the light relates to how much light energy is present at the surface of the water. There are a number of ways of calculating the amount of light you have or need in your tank, which are described below.
One of the more popular units of measure being used in literature now is the PAR (Photosynthetically Available Radiation). PAR relates to the amount of energy provided in the spectrum that is useful for photosynthesis. Unfortunately, there is no easy way for the hobbyist to directly measure PAR. This rating is most commonly used to compare the efficiency of one lamp to another.
The best way to actually measure the amount of light is to use a light meter made for this purpose. This type of meter measures lighting intensity in a unit of measure called Lux. A light meter will cost around $100 dollars. In general, the goal is to achieve a minimum of approximately 25,000 Lux at the surface of the water if keeping SPS corals with 20,000 to 40,000 being typical. Lower light tanks can get away with less. Measuring the light intensity using a light meter gives a completely accurate indication of how much light is really reaching your tank, however it is not really necessary.
One way to ballpark your lighting requirement is to use a watts-per-gallon calculation. This method is not as popular as it use to be since it does not take some variables into consideration such as tank depth or the efficiency of the light source, but it is still useful. You obtain this number by dividing the watts of lighting in your light fixture by the gallons of capacity in your tank. For a high light intensity tank, you should use a figure of 8-10 watts/gallon as your basic target. A lower light tank can get by with approximately 3-6 watts/gallon.. How does this compare with the typical lighting supplied by a tank manufacturer? As an example, a 55 gallon tank with one 4-foot long 40 watt fluorescent light which is a typical store bought configuration would have a watts per gallon of 40W x 1 bulbs = 40W total / 55 gallons = 0.75 watts per gallon! Now consider that you should aim for approximately 8 watts per gallon in your reef tank. For this 55 gallon tank, you would need about 55 gallon x 8 watts/gallon = 440W! That is about 11 times the amount of light provided by the store bought hood! Since it is physically impossible to put 11 40watt tubes above a 55 gal tank, it should be obvious that we need to find more efficient lighting schemes for our tank. If a low light tank is the target, you can see that the absolute minimum to achieve 3 watts/gallon would be 40W x 4 bulbs = 160W total / 55 gal = approximately 3 watts per gallon.
A better approach, especially when dealing with Metal Halide lamps is to size the lamps by the depth of the tank and determine the number of lamps by the square footage of the tank surface.
175W MH is suitable for up to 18” deep tank
250W MH for 18” to 24” deep
400W MH for anything deeper than about 24”
.
The other factor is the number of lights and the rule of thumb is that a MH lamp will illuminate approximately a 2’ x 2’ area of the tank. A 4-foot long tank would require 2 MH lamps.
wangotango
Active Member
and the above post works too
.
-Justin
-Justin