I'm new to the game. But am paranoid as fuck about PM.
Here's what I learned:
If your plants have it bad... its a lost cause. Kill'em, clean the room. Start over.
If it's not too bad you can try these options:
1) Sulfur burner
2) Alkaline Water
3) 10% Milk solution
4) Neem Oil (Einstein Oil, Fungicide3 etc)
5) Sulfur Spray (Safer)
6) Potassium Bicarbonate (Green Cure)
7) Bacillus subtilis - (Serenade)
Then there are a bunch of other chemicals and shit...
For me, my fans are on 24/7.
Good Luck. Let us know what works, or what doesn't ... and post pics!