I've been dealing with constant sinus infections, and a persistent thick yellow post nasal drip for the last year. I suspect it to be fungal, yeast or biofilm related. I used to work as a welder and breathed in metal vapor and smoke all day, and got a nasty sinus infection. it took several courses of anti-biotics to go away, but since then my sinuses have never been the same. I am no longer in such a bad environment. I've been drinking grapefruit seed extract (high it vtmn. C) and adding it to my saline rinse. 6 drops per 8 oz. I rinse twice a day. It has made a noticeable difference, however impractical. I still have a big fat brown glob to hork up in the morning though. I have started taking probiotics and fiber as well. I will be looking into inferfase plus. I also take a steroid sinus spray that has a noticeable impact as well, and would like to get my sinuses to the point where i no longer need it. I will keep experimenting until the problem is permanently resolved, that's all there is to do.