Yes, one would think a manufacturer of marine aquarium equipment would have the presence of mind to design their product with water/saltwater resistant/proof components. Most of course do, but they don't always get it right in the beginning & changes in design occasionally introduce issues. Generally a reputable company like Tunze or EcoTech will fix the problem in a hurry.

It never hurts to question whether something is safe or not though, regardless of who makes it. Many components that make up the product of a manufacturer are sourced out to 2nd & 3rd party producers.

Here's a photo of the 1st Generation VorTech MP40 wet side magnet. They were coated with a rather flimsy plastic film that would start breaking down & allow water to creep under the coating. Result is that the magnet would have to be replaced about every 6 months.

https://tsl4pa.blu.livefilestore.com...net.JPG?psid=1

EcoTech realized fairly quickly that this would "Not be the Mama" over the long term, so this is the new wet side magnet. No idea what the material is, but no more rust issues. And in the end, a little rust in the water is not a huge deal anyhow. The stuff many of us use to remove phosphates is essentially rust dust, iron. Note that the new magnet pictured was damaged in transit, got attracted to a conveyor I reckon. The package was a mess, arriving 2 months after EcoTech shipped the item with a letter of apology from Canada Post. Yay Canada Post.

https://tsl4pa.blu.livefilestore.com...net.JPG?psid=1

And here's the impeller of a "Penguin" powerhead, also poorly designed with a plastic coating that broke down allowing the metal beneath to rust & swell. The Powerhead seized up of course.

https://tsl4pa.blu.livefilestore.com...95a.JPG?psid=1

Thanks for the info Nick
Now I know why I wasn't worried about my Osmolator magnets
Guess I have the newer ferrite ones