Phoron overlay/amount impossible to clear

[BlueNexus]

When an area is contaminated by phoron, even after half an hour of siphoning by engineering, there is still usually about 0.003402 molecules of phoron left, and the phoron overlay (orange dotty thing) refuses to clear. Annoying as hell for engineering.

[ghost]

This is a result of tiles not correctly clearing their overlays. Can be fixed by an admin mass-modifying all overlays to change to default. As for trace phoron: this is due to syphons losing effectiveness as rooms reach low pressures. A correctly configured air alarm removing toxins from the room will work.