White stuff on fx4 rubber connectors

[Matth05]

Since I set up my fx4 I’ve noticed white film growing on both rubber connectors. I’ve cleaned it off before but it always comes back. Did a little bit of reading but no definite answers. Some people say algae or bacteria growth. And others say it could be calcium from hard water. Not too worried about it, just curious if anyone knows exactly what it is since it’s only on the rubber connectors and nothing else.

 

[Jexnell]

I had the same thing on mine. Never bothered the fish the years I had my FX4S.

 

[FahakaPapa]

In my opinion it's algae or bacteria. Calcium wouldn't clean off easily - it usually has to be scraped off and it usually ends up in areas that aren't completely submerged. For example my sump has some where the water splashes in between the chambers, but none on the glass that is completely under the water.

 

[FJB]

I get it too with 2 FX6s. Has not been any problem since 2017 and 2019, respectively.
It rubs off by finger, but some discoloration remains. I don't know the cause but I would also agree on likely algae or bacteria, or both. It seems harmless.

 

[IgnatzMcJockel]

Had that on my FX6, too.
Didn't cause any problems, but doesn't look that good either

 

[Matth05]

Thanks guys. Great info as always. Any idea as to why so much accumulates on the rubber of all places?

 

[Jexnell]

Thanks guys. Great info as always. Any idea as to why so much accumulates on the rubber of all places?

Probably because the surface is porous so is easy to colonize.

 

[bathawk]

have it on my fx4 and fx6 and a fluval 306.

 

[Trouser Cough]

That gray clay like film is called biofilm. A variant of what shrimp like to eat and some algae eaters.

It's not a sign of anything being wrong... the opposite is true.