Rust inside filter housing?

[LearningAboutPools]

I have a saltwater pool and I'm seeing some rust streaking on the inside of the filter unit.

Is this normal? (Picture attached)?
This is the start of my 2nd season.

 

[mknauss]

Very normal. Not unique to SW pools. All pools that use chlorine are SW pools.

Typically the rust is coming from the welds, etc. Not enough to effect your pool.

 

[JoyfulNoise]

Agreed with @mknauss … I see it all the time. If you want to clean it off, you can use Bar Keeper’s Friend liquid cleanser. It’s oxalic acid and it will remove the rust stains. Just rinse the filter out well after using it.

 

[Jimrahbe]

Matt, @JoyfulNoise

Once removed, is there any way to keep it from coming back? Some kind of paint or surface prep? Or??

Thanks,

Jim R.

 

[JoyfulNoise]

Matt, @JoyfulNoise

Once removed, is there any way to keep it from coming back? Some kind of paint or surface prep? Or??

Thanks,

Jim R.

Not easily. As Marty alluded to, it's because of tack welds used. When the stainless steel is heated to create a weld, it transforms the material from a stainless steel into more of carbon steel (both compositional and microstructure changes). While the weld is strong physically, the material loses a lot of its anti-corrosion properties.

You could clean it off with the BKF to get the oxide removed, shine it up with a melamine sponge (Magic Eraser) and then rub the surfaces with mineral oil to act as barrier layer but that will wash away over time (and no one really wants to put mineral oil inside their pool equipment ).

Welding is an art and a science. In technical high performance welds (think like aircraft engines and nuclear bomb casings), one would use multiple finishing and heat treatments steps to ensure that the weld is as close to the original material properties as possible. But these are cheap parts manufactured in bulk by companies that don't care about the technical aspects, they just need to make a product and ship it out the door ... corrosion is someone else's problem