Sea Water, Natural or
Synthetic?
(Which way to go?)
by Robert Fenner
Reprinted with permission, from Bob's website in San Diego: www.wetwebmedia.com
Aquarticles
Every few years a few standard "urban myths" (e.g. to float new arrivals or
not), seem to re pop-up in our hobby. One of my favorite, and most disturbing is the issue
of "real" seawater versus synthetic mixes. Here I'm referring to legitimate
formulations as opposed to "Wonder Water", "Magic Ocean", and other
sugar-based let's-raise-the-specific-gravity-gravity-without-increasing-the-ionic-content
mixes (supposedly allowing the successful co-existence of marine and freshwater
organisms). Nor do I mean to include "lobster" system water softener grade
formulations in this discussion. I mean here to disparage the claims of the purveyors of
so-called "natural" seawater. These assertions also apply for areas in the world
with easy access to the oceans where there arises the choice for the marine aquarist to
use a saltwater mix or natural water. There are, admittedly, many valid arguments pro and
con for either alternative.
Economics:
The better mixes can retail for 30-40 cents per gallon or more, depending on how much
you buy. "Live" ocean water costs the price of time, travel and proper
filtration for you to collect and process it, or typically somewhere @$1.00-$1.50 retail
per gallon to purchase.
In San Diego, free, sand-filtered seawater is available usually 24 hours a day at the
base of the pier at Scripps Institute of Oceanography, U.C.S.D., La Jolla. This service is
available at many other coastal towns. If you are dealing with large volumes of water the
dollar savings can be considerable in treating and using this water, but it does have it's
drawbacks:
Suitability:
More vital than it's expense is the water's relative ability to support marine life.
Most of the more complete mixes are capable of sustaining marines for extended periods of
time. The history of their use is impressive; they have been used all over the world by
science, public aquaria and hobbyists alike for decades. The best available salt mixes
have been demonstrated to support many invertebrates and fishes that live in close
conjunction with them without further additives or modification.
Natural water that is pH/alkaline reserve checked and, if necessary, adjusted will
support all forms of marine life.
Maintenance:
The strongest point against real seawater is that it "dies", both
biologically and chemically more quickly than synthetics. It's a fact; you must change
part of the water more frequently with natural water; depending on the size, type of
set-up, filtration, et al. 5-10-20% or more a month is often recommended. Many mixes
should be changed just as frequently, but often, especially in terms of appearance
(yellowing) you can "cheat" more than with natural water.
Another issue good and bad concerning natural water is that it comes ready equipped
with a multitude of micro- and macro-organisms. Even if the water is sediment filtered,
diatomed, U-Ved, ozonized, many "things" will survive. What to do then? One or
two things: 1) Place the water in a dark place for a couple of weeks before using. 2)
Treat the water with copper salts, permanganate, formaldehyde, chlorine, etc. and remove
the poisonous effects of the treatment before using. 3) Don't worry; consider the source.
Many dealers and hobbyists pour natural water, cold turkey into their systems with
impunity. I personally do not endorse item 3). I would treat all natural water as suspect
and quarantine and treat accordingly.
There are pro arguments to using real water with little critters or their remains in it
to start up a system. One point is that the time needed to establish bio-geo-chemical
nutrient cycling (whew!) is decreased greatly. Still another beneficial factor is the
ready seeding of the habitat for other microbial needs of the fishes, algaes,
invertebrates. Some of the naturally occurring tiny creatures that come in live water are
harmful, but most are either beneficial or benign in captive applications.
Natural water should be monitored for pH/alkaline buffering capacity at the very least,
and a supply of change water or chemical preparation be kept close at hand for adjustment.
Natural seawater, particularly supplies collected far from shore can exhaust it's
buffering capacity quickly (within a day).
The synthetic is in a word, convenient; it serves the purpose as a viable medium for
marine life and may be kept on a shelf and almost instantly made ready when need. Despite
claims to the contrary, there are little deleterious effects of not pre-mixing,
aerating... modern synthetic salt mixes prior to their use. Our corporation's service and
retail divisions have used thousands of cases of several brands over the years without
trouble for new set-ups as well as routine water changes. If the sea life involved is not
otherwise challenged or compromised, you should also have no difficulty.
Trace Elements:
Are a particularly contentious, confusing issue that continues (to my bafflement) to
perplex & impress aquarists. Edmund Mowka (1979, 1980) presents a concise, lucid
treatment of the subject. The long and short of it is it appears that most so-called
"trace" elements and compounds are:
1) Just that. Small, often transient materials of no or minuscule biological
consequence.
2) Readily lost by physical, chemical and/or biological mechanisms in captive systems.
3) Much of the "trace" benefit is derived from food/nutritive sources, not
from water per se.
4) For "reef" systems with substantial amounts of invertebrate and
intentional algae matter, must have chemical supplementation whether natural or synthetic
water is applied.
5) Basically, that there is no substantial valid argument for natural versus synthetic
regarding "trace"-elements.
A Conclusion:
This is not the whole story either, but it serves to illustrate the point. In my
opinion, unless you're dealing with very large volumes of water, want to devote yourself
to adequate preparation and monitoring, and consciously intend to put up with the vagaries
of potential pollution, pests and parasites, steer clear of natural water. Synthetic is
more convenient, cheaper in total cost, easier to deal with physically, lasts longer, is
safer, and it works!
Some folks assert that natural water must be best for "natural" livestock.
Maybe they think their aquaria are "little pieces of the ocean"; most systems
more closely approximate "little sewers". There is nothing phoney about using a
synthetic salt mix in an artificial environment.
A few references and further readings are offered listed to elucidate the history of
this "controversy", other arguments, and to provide a general background on
seawater itself:
Anon. 1974. Seawater. Aquarium Digest International. 2 (4) 1974.
Carlson, J. 1988. Seawater: What Every Marine Aquarist Should Know About This Fluid.
Marine Fish Monthly. 3 (4) 1988.
Dawes, J. 1989. The Salt Connection. Seascope. Volume 7, Spring
Fenner, B. 1989. Frequent Partial Water Changes. FAMA April 1989.
Mowka, E. 1979. Essential Chemical Elements. FAMA. April, 1979.
Mowka, E. 1980. A Fresh Look At Salt Water. FAMA. June, 1980.
Segedi, R. & Kelley, W. 1971. A New Formula for Artificial Sea Water. Marine
Aquarist. 2 (8). 1971.
Spencer, G. 1974. Advantages of Unnatural Water! Marine Aquarist Magazine 5 (1). 1974.
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