Understanding Lumen
Lumen is the measure of the total amount of
visible light emitted by a source. Lamps designed for human use are generally
rated in Lumens because this is the measure of light seen or used in the
application.
Why does Aquatic Life not rate their aquarium
light fixtures or lamps in Lumens?
Aquarium lamps and LED’s are designed to produce
special spectral outputs (wavelengths) required by the tank inhabitants. Not
all of these spectral outputs are seen by the human eye. Since Lumen only
captures the visible human spectrum, it’s not a good rating for the true
properties of an aquarium light. A better measure of light for an
aquarium application is Photosynthetically Active Radiation, often abbreviated
PAR. PAR designates the spectral range from 400 to 700 nanometers that
photosynthetic organisms like corals and plants use in the process of
photosynthesis.
Understanding PAR
Put simply PAR ( Photosynthetically Active
Radiation) is the amount of usable light measured in photons that falls
on a square meter in a second between 400nm and 700nm.
This information is very useful as certain
corals, clams and even plants require different amounts of PAR to thrive.
Mushrooms and other soft corals for example do well getting PAR around 50-100,
whereas certain shallow water SPS species need PAR values of 500. Have you ever
wondered why it appears that some corals seem to not grow? They might not be
placed in the aquarium properly and may not be getting enough light.
For these reasons it is important to understand
how much PAR is in your aquarium and each animals requirements. Too much or not
enough light and your photosynthetic corals and plants will not be happy.
There are a few different PAR meters on the
market and they are relatively inexpensive. They are a great investment and
easy to use. A meter can help you to acclimate new corals and know where the
best placement is for each animal.
Sincerely,
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