This is what I found under the plastic diffuser of my airfit f20 Quietair elbow after 30 days of use and cleaning daily. I only found this cotton type mesh under the plastic diffuser cap by accident when inspecting it after cleaning, otherwise I would never have known it was there because the elbow is not meant to be disassembled. I think this is a design flaw because apparently there is no way to clean or replace this mesh type filter. Not sure if it's mold, but does look like can cause clogging of the exhaust port.

"dirt".

From your lungs, and dirt that gets past the cpap filter.

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After reading this post, I soaked my f20 elbow in dish soap, used a water flosser to flush out all the soap, then blasted it with my air compressor... I think that should be able to handle any potential blockages in the future... or any icky growth. But I agree this looks like a design flaw. Unless this was meant as a consumable and meant to be replaced every so and so months. But its not marketed as such.

Well, the bright side? The dirty air is not getting put back out into the room

Looks like I might be swapping these out every so often now.

Unless your intake air filter has even come close to the same colour, what you are seeing is most likely mold. Resmed recently changed the design of the diffuser and the new version restricts the exiting air more than the old one. If you reduce the amount of old air exiting the system then you're reducing the amount of fresh air that can get in. The marks on the foam are an indicator of very high humidity in the air exiting. In the "Quiet Air" diffusers Resmed made the diffuser exit holes smaller in addition to adding the foam. The result of this restriction increases the humidity of the air that exits through the holes. I suppose that people who use a higher setting than myself might have an issue with the amount of air exiting with the old design, but reducing the air flow compromises air quality for people using a lower setting.

I stopped using mine after only 4 nights because I was getting water buildup in the mask and the hose. Thinking this was something I was doing, I tried several different settings including with no water in the humidifier and the hose set to the warmest (30C) setting. I still got water on my face and in the hose (and the hose was quite warm too). If there's that much water in the hose that means I was rebreathing stale air. I opened up my diffuser and it looks just like yours. After only 4 days use! I'm still using the old diffuser with new masks and I've never had an issue with humidity despite setting the humidity higher and the hose temperature lower. Thinking that my issue could be a "one off" defect with the new diffuser, I continued to use the old one and not pass judgment on the newer design until my next mask arrived 6 months later. I didn't use the diffuser so it's clean, but the holes and the layout are exactly the same.

You can see from the pics that the new version has significantly smaller holes and channels for the exiting air. Also, the old one that I'm using has been in use for nearly 18 months. When it's time to replace it, I'll either switch the brand of masks or start drilling holes in the new ones...

Unless someone has *examined* the spots, then wild guesses serve no purpose and is just alarmist.

I used the F&P Piliaro Q mask for a while, it had a white mesh filter diffusing the air output.

Guess what, it got dark dots where the mesh was overlaying the holes in the mask itself.

It happens, it wasn't "mold", it didn't grow.

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