[Puzzdre]

Thx for the info on BECooling Jtroutma!

One thing comes to mind, the goal with sanding fans is to smooth the surface and gain less hiss of the air being pushed through the fan. Maybe you could try to lacquer the fan parts in one or two thin layers to fill the gaps (in the end, same thing you get with sanding). Two thin layers should do the trick and would not add much mass to the impeller.

Think that I'm gonna try it once my tygon arrives (thx again for link), and I dismantle my system for tube change...