How bad is a little rust from a magnet?

[Shobloth]

Recently installed a tunze ato and looks like the company forgot to coat the magnets on this one ( I have 2 more from them and they are coated) I recently noticed a rust stain on the sump about the size of a dime and immediately took it out. What would it have done while it was in? (About 3 weeks)

I had a ricordea inexplicably die and a nem acting strange. Also had an angel get cloudy eye. Further had an inexplicable ph crash.

Anything I can do to minimize damage?

 

[bertoni]

I probably would run fresh carbon and possibly a PolyFilter. The coral issues might be due to metal contamination. I think that the fish infection likely has another cause.

 

[oldsaint]

Which top off do you have?
Tunze power heads have one mag coated and one is not. I made the mistake of not looking and pieced together the non-coated one to go into the sump. I run two of the large osmolators and don't remember having to put anything together. But, I could see them using a coat and non-coated mag in the nano top off.

 

[Paul B]

I guess I shouldn't be the one to answer this question.

 

[dkeller_nc]

I'm pretty sure that the Tunze magnets are ordinary ferromanets (i.e., not rare-earth neodymium magnets). Ferromagnets are alloys of iron, cobalt and nickel, with possible other metals as trace elements.

The iron shouldn't cause much in the way of issues, as it's not particularly toxic and is very insoluble in seawater with a typical pH of >7.8. Nickel and cobalt aren't likely to cause much issue either unless present in very large amounts (very unlikely from surface corrosion of a magnet).

A bigger concern would be chromium if it was an alloying element in the magnet. Fortunately, water changes will remove most any contaminating metal from a reef tank if the new water is made from pure RODI and a decent salt mix.

And the corrosion you note is very unlikely to have caused a pH crash - there's just not enough quantity to do that.

 

[Hal]

I wouldn't spend more more minute worrying about rust. I just added one cup of Grannular ferric oxide (a.k.a. "rust") to my tank yesterday. I'll do it again next month.

 

[bertoni]

I agree that the iron is safe enough. Other elements in magnets seem to have caused problems for other people, though, and certainly some metals are very toxic to invertebrates, like copper and zinc, for example.