View Full Version : Tunze 9004

01/05/2017, 11:23 AM
Hi I noticed when I removed my skimmer to clean a couple magnets and area were rusting on the actual skimmer that is submerged. Tried cleaning it but no go.
The skimmer now is probably two years old. Is it the magnets that are bad or I actually read if you run GFO (iron based) it could react with the magnets?

01/05/2017, 11:30 AM
GFO is rust, it is just rust (ferric oxide) in pellet form. The iron particles are attracted to the magnets. The magnets are ceramic and cannot rust but they have an iron plate under them to bridge them so they act as one magnet, this plate can rust but it is not common. The way to tell the difference is the iron plate rusting will generally make a stain that lookalike a bullseye from a point source, that would be the hole in the coating that the water is getting to the iron plate at. If it is GFO or attracted iron, the staining will be wide spread and flaky and it will clean off with sufficient time in vinegar or CLR and some scrubbing with a toothbrush. This happens more pronouncedly on the older ferrite magnets because the surface is rough and 3 dimensional. The coated magnets we use now are smooth so less sticks.

01/05/2017, 02:26 PM
Oh ok. I did pop off one of the magnets so I could try and clean the area around it. Basically it's mainly rusted around the one magnet. I did soak it and tried brushing it off but not as easy as i thought. Not flaky but sort of encrusted on. I have the skimmer back in the tank but I will remove it in a few weeks and look at it again and re-soak. Been using the iron based GFO for over a year. Recently have been trying the aluminium based.

Would you know if this "rust" would contribute to a coating on my rocks and sandbed. Like a diatom bloom.

01/05/2017, 03:09 PM
I suppose the finer dust could cause some staining on the rock etc but that is not something I have encountered before. I would be more prone to thinking it is diatoms. GFO is generally superior to Aluminum based phosphate removers, aluminum based gets hot, the aluminum irritates corals. Iron is far safer, in very high doses it could feed more complex algae (macro algae) and might harm some corals and inverts but it has a very high margin of safety, keep in mind corals grow on rusting iron ships and oil platforms, but I have never heard of them growing on aluminum. I would try CLR, it is phosphoric acid and detergent, as long as you rinse well it is safe to use.

01/05/2017, 03:19 PM
Ok .....thanks for the help and info.