I also use colloidal silver in a netti pot for sinus infections. I have never used Oil of Oregano for sinus infections but I would bet that you wouldn't want to use very much (like a very small drop in netti pot) because it is really powerful stuff. I use my sinus wash/netti pot 3 times a day or more when I have a raging sinus infection. A friend of mine works in ENT and she tells her patients to use 1tsp of apple cider vinegar in a full netti pot/sinus wash.