dirt in Heiki roof vent

Has anyone got a cure for what looks like sand or grit between the two layers of my Heiki roof vent.
It doesn't appear to be damp or condensation, just dirt.
No cracks or damage to the window.
It's annoying to look up through a clean window, both inside and out, and still see 'bits of grit'.

For some inexplicable reason I have water getting into the void between the rooflight leaves. As it's a brand new van the rooflight is going to be swapped under warranty. The only thing I can think of in my case is an iffy seal where the fastenings are attached. Quite how dust has got into yours though is another matter, and I'm afraid I can't think of a fix.

Hi Justin, Hope we are talking about the same vent? If so perhaps my recent post will help along with the replies: Nuevo Roof Vent 2

https://www.autosleeper-ownersforum.com/t29706-nuevo-roof-vent-2