- Properly light a reef tank is one of the most
important considerations when planning a new aquarium
or upgrading your lighting set up.
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Hi, this is Wayland from Marine Depot
and thanks for tuning in.
There's a lot of information to sift through
if you're looking for lighting answers online.
The science of light and corals is very complex
and can get very confusing, especially
when you're looking for straightforward information.
At Marine Depot, we get thousands of questions every month.
Reef lighting is certainly at the top of the list.
We are commonly asked what type of lighting
do I need for good coral growths?
And which lighting fixture is right for my tank?
Although there can be a simple answer to these questions,
it's important to understand the science
that informs these decisions as well.
Pretty much everyone knows that light is critical
for keeping SPS and LPS corals.
Many new reefers though, tend to blast the corals
with as much light as possible, which research
on captive coral show isn't ideal.
In the early days of reef keeping, aquarists
bought the biggest, brightest light they could find.
Everyone knew coral reefs thrived on direct sunlight,
so DIY reefers were trying to hang
the power of 100 suns over their tanks.
That's what the public aquariums were doing,
so why not try the same thing at home?
But it didn't always work.
The light overheated the water, some corals stopped
growing and others were burned.
When it came to light, more definitely was not better.
Today we understand a lot more about lighting requirements
of corals and other photosynthetic invertebrates.
We tried to distill all this information down for you
to make choosing a light less of a headache.
The major factors to keep in mind when looking
for a light are wireless controllability,
programming modes and a sleek form.
However, the king of all these factors is the light's PAR,
which is the first thing you should look at.
PAR stands for photosynthetic active radiation.
It is the range of light waves used by symbiotic algae
living inside of coral tissue.
PAR is the engine that drives photosynthesis
and it's photosynthesis that feeds our corals.
If your lighting rig is bright, but doesn't
provide the right light spectrum,
all you're doing is burning electricity.
Quality beats intensity.
PAR covers the visible lighting spectrum
but is heavy in the blue 400 to 500 nanometers,
and the red 600 to 700 nanometers wavelengths.
It is possible for a light to be bright but not provide PAR.
PAR is measured in units of micromole
photons per square meter per second.
Thankfully there's no math involved
in figuring out a fixture's PAR rating.
Most of today's top LED light manufacturers provide
PAR specs for their fixtures, making life a lot easier.
They get these measurements by using a PAR meter.
The sensor is first placed in the water under the light.
Readings are then taken at various depths and distances
from the center of the LED array.
PAR readings are then plotted to show how the intensity
of the PAR drops as you move further from the light.
You can use the manufacturer's PAR data
to get a rough idea of the amount of light
your tank will receive with a particular light fixture.
You can also take your own measurements with a PAR meter.
PAR meters are a little pricey, but they do let you
see the PAR measures at different levels in your reef tank.
It's very helpful for determining where to best place
your corals, or to make adjustments to your light.
So what's the right amount of PAR for your corals?
Marine biologists have conducted PAR measurements
on tropical reefs were SPS and LPS corals thrive.
The PAR levels range from around 150 to over 450
across the reefs of the world, but what level
will most satisfy corals in a home aquarium?
Captive coral research Dana Riddle discovered
that the ideal average PAR range for corals
is somewhere between 100 to 200 PAR.
Too much PAR is both ineffective and actually it inhibits
photosynthesis, potentially damaging corals as well.
200 to 400 PAR will bring up vibrant coloration
but sacrifices a little coral growth.
Research suggests that corals may even develop
brighter pigments to protect against excess lighting.
The big takeaway is captive corals are happiest
with moderate light intensity.
Too much light will inhibit or harm the corals.
There's no absolute rule on the perfect PAR for all corals,
but a good starting point is 150 to 250 PAR.
So how do you choose a right light fixture for your tank?
Start by looking at the PAR specs.
They'll give you an idea of
the maximum PAR at specifics depths.
There's also nothing wrong with going with a more powerful
fixture as long as you can dial it back,
which is especially helpful as your corals
acclimate to a new lighting system.
If you can't find PAR data for a particular light, search
online and see how other aquarists are using the fixture.
Learning from the experience of others
is always helpful and valuable.
If you still aren't feeling too confident on lighting,
feel free to give us a call and
we'll be happy to help you out.
Please share this video if you found it helpful,
and don't forget to like and comment below.
As always, take care and happy reef keeping.
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