Okay.. to answer your question, I will break down what i feel are the two most important values when building or choosing LED lighting for your home aquarium. I am sure most other lighting professionals will concur. First I will attepmt to explain the spectrum of light at various depths in the natural ocean. The most commonly used unit of measurment pertaing to the spectrum of light (also know as the temperature of light) is the Kelvin. At 0 degrees Kelvin, there is no light. Moving up the scale from 0 is when light is produced. As light waarms from 0, red light is produced. As the light grows in warmth, starting with reds, it continues on to greens followed by blues and then violets. The sun itself at mid day produces an approximate 5500k. The higher the kelvin, the greater the warmth of light. In nature at a depth of 15 feet the majority of reds and oranges are absorbed by the water. Continuing to a depth of 30 feet yellows are then absorbed. At 50 feet the greens have been absorbed leaving only blues and violets. Beyond 50 feet light will be at its highest kelvin until it eventually tapers off into the depths. Though Kelvin measure the color temerature of light, there is another means of measuring the intensity. LUX is the intensity of light that impacts any surface. In impacting water, LUX helps us determine the penetration of light. The sun itself produces 120,000 LUX, but due to changing weather patterns and such, it would average at around 75,000 LUX. As light hits the surface of water, wavelengths are absorbed and the intensity of light slowly dissapates into the deep. The clarity of your water will effect the penetration of your lighting. That is why water changes are so very important to good light penetration. There are LUX meters out there some cheap and some not so cheap but most being relativly accurate. But if you do not have a meter or are trying to calculate intensity before setting up a fixture, i can kind of help with that. In relativly clear water, light intensity at 15 feet will average 20,000 LUX, at 30 feet 10,000 LUX, and so on... Knowing where your corals grow in nature will help you determain what type of light temperature (kelvin) and intensity (LUX) they will require in your home aquarium. In figuring this, we will convert the wattage of our fixture at surface to an approximate LUX.
1 LUX = 1.46 milliwatts of energy at a standard 555nm with a light surface of 1 meter
or
1LUX = 0.00146 watts/sq. meter at 555nm
or
1 LUX = 0.0001389 watts/sq foot at 555nm
The only problem with this basic calculation is that the lighting of your home aquarium emits many differant frequencies leaving us no fool proof algarythym to calculate to exact LUX of our home aquarrium with out the use of a test kit. But we can use this simple method to approximate a lux reading without having installed a fixture. The LUX also determains how high above the surface water our fixture will need to be mounted. You will need to factor in your tank dimensions as well as the arc of light your fixture produces in order to assume a more accurate figure. Most coral we collect in our home aquariums thrive at a depth of 15 to 70 feet below waters surface. At those depths your primary color temps are going to be blues and violets. So in choosing a lighting option using a DIY LED lighting system, you will need to figure in the color spectrum your specific livestock will require. Typically a majority of blues and violets adding whites only for viewing pleasures. Adding reds, oranges, and yellows can stimulate growth in some but brown others. So I suggest being cautious adding too many reds oranges and yellows. I personally reccomend Blues and Violets. I cannot tell you exactly what will be best for you, Only you know your system and livestock. In determaning your spectrum (kelvin) and penetration (lux) you should have no problem building a fantastic Lighting option. I hope that i have helped answer your question, if you have any others, please dont hesitate to ask.
