I reuse my PBW until it is gunky. PBW has 2 cleaning components, a low strength caustic, and the O2 part. Admittedly it is not as effective after the O2 is gone. I doubt aeration would work, i think the o2 comes from something like hydrogen peroxide. You could try and add some oxy-clean, hydrogen peroxide or just longer contact time/agitation.
thanks weird, I have been using oxyfree for a while now. I picked up a slight sour twang in my last batch so I thought I would switch back to PBW for a while.
I dont think it has the low strength caustic that ulrich was talking about, does it?