Magnet is rusting?

[GSMclowns]

Hello,

I have a pair of 6015 Nano Stream in my 29 gallons BioCube tank. I have them for 9 months or less and have been running great. But I just discovered that the magnet is rusting. These magnet aren't cover at all like the magnet from my other 6105 pumps. These magnet are just glued to the bracket. So was this a mistake or all of them aren't cover with rubber or epoxy? Will the rust have any negative effect in my tank? I took them out of the tank now but certainly don't want to throw them away. What should I do? continue to use them or throw away the bracket that hold the powerhead and buy new bracket?

Thanks,
Bao

 

[rvitko]

First, this type of magnet was not coated. It is the same type of magnet most impellers are made from, ferrite, which is a type of manmade magnetic ceramic. They are not coated as they are weaker and any additional barrier weakens them further, this material cannot rust.

One of the following is the issue here:

1) The magnet picked up something that is rusting and this is the most common issue. I have even had brand new magnets out of the box have some iron filings on them that they picked up at the factory and they can just as easily pick up iron filings or steel wool dust in a kitchen or garage. The single most common source though is GFO, which is nothing but pelletized rust, it will stick to magnets and cause a stain. This type of stain has a couple hallmarks, it is wider spread, generally along the edges, and usually has an area that is flaky (the actual rusting debris attracted to the magnet). In this case the solution is to just soak the magnets in a mild acid and use a toothbrush and avoid contact with the source of the iron particles.

2) The magnets rest on a plastic coated iron plate, in some cases their is a small breach, a pinhole in the plastic resin and the iron plate rusts. It is only a plain iron plate, it has no plating of nickel or zinc or otherwise toxic metals. The end product of it rusting is exactly the rust we use as phosphate remover in reef tanks. If this is the cause the rust stain will lack any flakes and will be in a ring, creating a bullseye like stain emanating from the hole in the resin. In this case we should replace the magnets.

 

[GSMclowns]

So in another word, my magnet is perfectly safe to use. Its not rusting at all but only picking up other dirty stuffs that make it looks like rust?

 

[rvitko]

The rust would be only iron rust, which is relatively benign but I would not say harmless, in high levels it does seem to negatively impact corals, but with that said, we use it when we use GFO and corals do grow on rusty ship hulls and oil rigs. I would try cleaning it, if it reoccurs, it is possible that the iron plate inside is rusting and we would need to replace it. The most probable though is it just picked up some iron.