Natural Seawater

Natural seawater (or NSW) is water harvested from coastal areas, usually by boat or small ship, a kilometer or so from the mainland, and hopefully, well away from pollution from sewage or industrial waste.

The use of natural seawater, either for new tank startups or for routine water changes, seemed to gain its share of advocates a few years ago. The commonly held belief was that using it resulted in a healthier aquarium by seeding the tank with natural beneficial microbes and was better for the fish and corals.

I’ve even heard one aquarist swear that using only natural seawater in his aquarium had a calming effect on the fish!

But today, only a few LFS’s make it a point to make natural seawater available to their customers. And, some might say, for good reason.

Natural Seawater | Do The Benefits Outweigh The Disadvantages?

Unfiltered natural seawater is basically alive. When harvested from a clean area, away from pollution and ships and provided it makes it into our tanks within hours, is probably the best thing you can put into your saltwater aquarium.

But such a scenario, as you can imagine, is not possible, unless you’re fortunate enough to live next to a pristine coastline and you have your own boat where you can venture out to collect your own seawater when you need it. We should all be so lucky!

Natural Seawater

Natural seawater used in a public aquarium

A gallon of seawater is swimming with millions of tiny microbes, bacteria, phytoplankton, zooplankton and even gametes and eggs of fishes and corals. After the seawater is harvested, many of these organisms start to die, altering the biological and chemical nature of the water.

For this reason, harvested natural seawater must be sand-filtered, UV-sterilized and stored properly.

Very few LFS’s who sell natural seawater have the facilities to treat and store it properly and are selling the water au naturel. Not to mention the fact that the consumer has no way of verifying that the source from which the water was obtained.

As you can probably now tell, my take on using natural seawater is simple — why risk it?

Natural Seawater And Public Aquariums

The biggest users of natural seawater are public aquariums that require such large amounts of water that it would be highly impractical to use an aquarium salt mix. Of course, such aquariums also have the means to filter natural seawater through large silos of sand filters, followed by a good zap with industrial-sized UV sterilizers to kill potentially harmful bacteria and microbes.

Buffering Natural Seawater

The buffering capacity of natural seawater — its ability to hold its pH and alkalinity levels in an aquarium environment — is very low. And this is another key area where natural seawater loses out to commercial salt mixes.

Drastic swings in pH and alkalinity are common when using natural seawater so regular monitoring with a digital pH meter is a must. The aquarist who insists on using natural seawater must have on hand pH and alkalinity buffers at all times.

Pre-Packaged Natural Seawater

A few years ago, Nature’s Ocean, the company that brought us Bio-Activ Live™ Sand, came out with Nutri-SeaWater® Aquarium Saltwater.

Touting the advantages of instant water changes with no mixing and containing millions of live marine bacteria and trace elements, it also used a patented process where the denitrifying bacteria were kept alive and ready to do their thing when introduced into the aquarium.

But Nutri-SeaWater® didn’t exactly turn the saltwater aquarium hobby on its head.

The main issue, I’m guessing, was cost. The product wasn’t cheap because of the cost of shipping, and most aquarists who were using good, high-quality aquarium salt mixes probably weren’t convinced that this product could be any better than what they were already using.

Interestingly, Nature’s Ocean claims that Nutri-SeaWater® is harvested natural seawater that is not treated with carbon that can strip trace elements, or UV-treated. At a specific gravity of 1.027 and a guaranteed pH of 8.3, Nutri-SeaWater® could very well be the hobbyists answer to finally reaping the benefits of natural seawater, with peace of mind.

More pages on Saltwater Aquarium Maintenance:

Algae Control

Feeding Marine Fish

Water Changes

Mixing Saltwater

Deionized Water

What To Look For In An Aquarium Salt

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