Water au naturel

In the last few years there has been an unfortunate trend to introduce so called “reef” salt mixes to the market. It seems like most manufacturers have these available. Most of these have elevated calcium and magnesium concentrations, added trace elements, vitamins and other organics. Once again we do not learn from history but seem to think we know it better than mother nature and at least some of us seem to think it is possible to make coral reefs even better by using some man made modifications to the environment they have evolved in.

The main reason for this post is that some time ago I learned my favorite salt mix manufacturer, Wiegandt GmbH (hw marinemix professional) whom I thought was above all this reef mix stuff, was going to introduce their very own salt mix formulated especially for reef aquariums. Like we weren’t able to keep magnificent reefs with the more natural mix! I’m guessing the reason for this is they made small modifications to the mix for Tunze relabeling and now want to introduce the same product under their own brand. The hw marinemix professional has always been very close to natural seawater (NSW) in its composition and has worked fantastically so I can’t really understand the need for another mix.

Maybe marketing people just got bored?

Reefs have seawater, not reefwater

Reefs exist in a sea, not in some imaginary special place. The water on reefs is usually higher on organics (especially particulate) but the inorganic components are the same for most healthy reefs. The only “special” chemical feature of coral reef waters is that they are always low in inorganic nutrients. High inorganic nutrient concentration will shift the balance towards algae dominated reef and corals will be outcompeted by them. The factors that really control the formation of a reef are substrate, light, temperature and water flow, not the chemical composition of water.

Funny thing is that most of us ignore these vital parameters. Almost no one has PAR meter, do not report water flow velocity and come up with some ignorant guidelines for dissolved nutrients that are hundreds of times higher than in nature. Many of us measure for example the calcium concentration with great precision but really don’t know how much light a coral receives or don’t ask how many centimeters the water should travel per second.

Yet it seems that salt manufacturers are convinced that by modifying the only truly stable variable, chemical composition of seawater, your aquarium will flourish.

It’s impossible to fix incorrect with more incorrect

If the salt mix you are using is not manufactured to be close to natural seawater, how are you going to fix problems in case of element imbalance, accidental overdose of some supplement or any disturbance? Do you really want to add more organics and trace elements or raise calcium concentration abruptly if you must do a larger water change due to some unfortunate death in the tank?

With a natural salt mix you will always move the water chemistry towards NSW and with “reef” mixes away from it.

Chemical balance is the key

As said, corals and other reef organisms have evolved in an environment that is constantly changing except in one regard and that is the inorganic chemistry of the seawater. I think it is sometimes forgotten that many reefs experience daily fluctuations in light, water flow, oxygen, pH and even temperature and salinity. Some of these change seasonally even more. Yet it seems that many hobbyists do their very best to keep these stable but choose to ignore the chemical composition by using a salt mix that will introduce large chemical changes with every water change. Some might even be proud to claim they don’t need any supplementation between water changes which means that the delta between concentrations is even bigger.

Some think it is better to have more calcium, magnesium, and alkalinity in an aquarium than exists in nature. I personally think this is an idea straight from a mental institute outhouse but even if I didn’t, I would certainly not want to target calcium concentration of 500+ ppm which would only result in large amount of abiotic precipitation.

Don’t dose anything you can’t measure?

One of the inconvenient truths of the hobby is that salt mixes are not reliable. Even the largest manufacturers struggle to get the major components of a salt mix right every time. For example, the magnesium concentration can fluctuate a lot between batches and magnesium salts are one of the major components of any salt mix. It just boggles my mind that elements like magnesium are not controlled more closely because a difference of +-100 ppm Mg must affect many other parameters as well.

Of course this is a problem for both natural and “reef” salt mixes, but do you really trust the manufacturers to be able to add the extra trace elements and organics more accurately than the major components that are measured in kilograms and not in micrograms? And if they don’t care enough to get things like magnesium right, how could you trust them to do opposite for less important components?

…

So, I guess I’m not too exited about the so called “reef” or “enhanced” salt mixes. I honestly can’t think of any real benefit of using them, you’ll just make your life harder by introducing yet an other variable that you must keep in mind. It is much more easier to control each element separately plus I think it is beneficial to try to keep chemical balance in check. Why don’t manufacturers provide their magic reef powder as a separate component so that people who think they need it will be able to buy and add it to the freshly mixed water?

Tags: chemistry, grumpy, Husbandry, tank

This entry was posted on Wednesday, May 20th, 2009 at 19:16 and is filed under Husbandry. You can follow any responses to this entry through the RSS 2.0 feed.