I had an infection in one of my fermenters, stripped the posts and PRV gave the fermenter a good clean every thing was fine. Using a different fermenter on another brew, got the same infection. Realised it could be coming from the tubes and Blowtie as I start at negative pressure, sure enough after cleaning I was rid of any more infections. Easier to clean all the accessories to the vessel than to throw out a brew. The PRV's are an easily cleaned itemWhy are you cleaning it so often?
If krausen is getting in it, it will surely get in the PRV as well?