Have used it a number of times. Always worked perfect, including the last time I used it last October. After that trip, I sat it on the wood stove mantel and let it dry for a couple wks before packing it away with the rest of my backcountry kit for the winter.
Last Sat on the trail, what was once a nice steady flow in gravity mode, became a very, very slow drip. Squeezing, which I don't like to do, only produced marginally better results. Since I was coming back the same way, I stashed the filter to save weight and picked it up on my way back.
Again, this thing worked perfectly last Oct. Don't recall if I back-flushed after that trip but have a few times before, even though I have only used it in clear mountain water.
Seems I recall reading here that someone else experienced something similar. Is that the case? Anyone have any ideas before I contact Sawyer? I have not tried to back-flush, yet.
Pretty bummed as this seemed to be the perfect filter.