advanced aquatics | J. CHARLES DELBEEK
Big Reef,
ater quality” can mean many things to
many people. For some it is the appearance of the water: if it is cloudy or tinged
with color, they assume the water quality
is poor. And, if the water is crystal clear and
colorless, then the water must be good. Unfortunately, this is not really true.
Water that is cloudy or colored can actually have
excellent water quality and water that is clear could be
terrible. Having made more than 400 dives in both the
W
Close-up view of the side window showing a collection of LPS
corals taken February 2, 2010.
trite, nitrate, pH, and temperature have been measured
for decades. It was not until we started keeping live corals that other parameters such as calcium, alkalinity,
phosphate, strontium, iodide and now dissolved organic
carbon (DOC) were added to the list of measurements.
Water clarity in most home aquariums is usually very
good—it takes a major problem for the water to look hazy
and difficult to see through. This is solely a function of
the viewing distance since at most we are looking through
a few centimeters of water. But if you look through several meters of that same water you will see
that the water is not really clear.
This is the curse of large displays such as
the 200,000-gallon reef display at the new
Steinhart Aquarium at Golden Gate Park in
San Francisco where I work. The maximum
viewing distance is about 30 feet ( 9 m), and
any particulates in the water cause a drop
in visibility. With over 2,000 fish and 1,000
pieces of coral, it is easy to understand that
there could be water clarity issues. I don’t
think we really need to have gin-clear water
since this is what most wild reefs look like.
Diving in the tank, I find that it is very
clear, except when looking horizontally
over a long distance—not unlike a real reef.
This is not to say that it might not be an
issue since we are not completely sure what
is contributing to this reduction in water
clarity. It could be calcium carbonate fines
from the calcium reactors, excess calcium
hydroxide, detritus suspended by water motion or dust and other sediments coming
from the public viewing space above the
tank. Only filtering the water over a fine
filter disc and examining the residue will answer that
question…maybe.
Pacific and Atlantic, I can tell you that very few, if any,
reefs would pass the water quality test if it were based
solely on clarity and water color. It’s time we differentiated between water quality and water chemistry.
“Water quality” should be used to describe the actual
water chemistry. Basic parameters such as ammonia, ni-
WATER SHADES & DOC
Water color has also been an issue. Over the months of
operation, the water has gone from clear light blue to
a greenish/yellow tint. This was discussed in a previous
CORAL column on ozone (November/December 2009).
Since we started running ozone in December 2009, the
