[leebca]

Matt,

You may wish to contact Anthony Calfo. As I understand it, he recommends trace element supplements. So he probably has some sort of addition plan. (I'd hate for you to rely on my shoot-from-the-hip recommendation. )

Anthony doesn't use trace elements himself because he does 100% water changes every week. But I don't think too many people do that!

He uses Instant Ocean, but I think if it wasn't for the cost, he'd use Tropic Marin (the salt I use).

[greenbean36191]

Lee, I disagree.

There is a lot more to this question than just static numbers. Yes, some levels are below NSW and some are above, but what are those elements and what do they do? The answer for most of those elements is that we have no clue about benefits at normal levels, but we do know about toxicity at elevated levels since most are concidered heavy metals.

Also, just as important as the fact that an element is being depleted is who is using it and how. Is something really essential because it can be taken up or is it just taken up opportunisticy or to minimize toxicity. Corals uptake significant amounts of Sr and use in their skeletons in place of Ca when it's available, but it slows down calcification. Crustaceans take up iodine, which is toxic, and sequester it in their exoskeletons where it's less toxic to them, but it certainly isn't essential.

In any event, dosing a tank with trace elements is horribly inefficient. Most animals, especially the higher ones like fish, are terrible at taking in waterborne minerals. They get them through bioaccumulation in the food chain. Algae on the other hand are very good at taking things out of the water column. Unless you are culturing live food in the tank, most of the trace elements are going to the algae rather than the fish (even with herbivores, as a rule of thumb, only 10% of primary production makes it to the next trophic level). Almost any food you can add to a tank already has trace elements bioaccumulated in it since it came from something alive. You're already adding trace elements in a form that is much more available to your fish just by feeding them.

Bottom line is this. It could hurt to dose trace elements, if nothing more than your pocket book. The elements that fish need they already get from their food, the rest we really know nothing about. Why add something that could be potentially toxic and has no known benefits, especially when you have no way of testing or accurately managing levels?

As far as Julian Sprung is concerned, I know he's got a BS in zoology, but I'm not sure how much he's formally trained in marine specific fields, so I'm not sure how reliable of a source he is. I think of him more as a very experienced and pioneering hobbyist than an expert on the more technical aspects. Also, as someone mentioned he has a vested interest in the matter as well.

[leebca]

I appreciate your perspective greenbean and I appreciate the fact that much of what the fish gets is through eating.

I believe that it is important to keep the fish in the water with the elements is have evolved with over the centuries.

You're right about what humans don't know, so is it wrong to put into the water what is naturally there just because we don't know? Do we know enough to do this? You're right about the authoritative, educational or competence of those who propose things in this hobby. But we do defend opinions with anecdotal information from people with absolutly no credentials other than they are in the hobby for a long time.

What I defend my opinion with is test data and the fact that Nature put it there to begin with. Whether Nature knows what it's doing or not is not my call.

I maintain my tank water with the known essential elements in the levels of NSW or above.

It's convenient to say this is not right because:
1) We don't know
2) We can't measure (at home)
3) There is anecdotal info that it doesn't seem to be needed
4) People are trying to sell products

But what I believe to be right is to keep my fish in water with what they have lived with for the last several centuries for these reasons:

1) We don't know if it is important to them or not
2) It can be measured (laboratory)
3) Anecdotal information doesn't mean the fish couldn't be better with it
4) People sell many things, including marine aquariums, but it's up to the aquarist to make up their mind.

If the aquarist is making regular water changes, the water element concentration stabilizes from those coming in with the new salt water and those being added. The concern you have about it accumulating too much is valid. I have measured it and it isn't accumulating. It reaches equilibrium with the water changes.

Where the elements are going is another valid concern. I'm not that interested in this other than to say that it needs to be in the water as it has been for centuries. I don't claim the fish are using these elements (other than studies done to show that the essential elements are needed by marine food fishes). I'm just keeping them there.

Like I mentioned before, disagreement is healthy. You can disagree from anything you can think of, but I'm going along with Nature on my opinion.

My choice is to maintain my saltwater with the essential elements in concentrations near that of the sea. This has yielded healthy, disease resistant fish. I would recommend the same to others.