I have used a Sawyer mini in gravity mode. I don't use a long tube either. It filter plenty fast. I attache a bladder with and adapter to collect clean water. Because it is a closed system the water flow stops when the receiving bag is full, so I just let it set while doing other stuff. When I come back, it's done. Also, air will not pass through this type of filter, so your flow rates are slow if you get an air bubble in it. I suck on the clean side like a straw while jiggling the bubbles out of the filter until I can feel it is flowing smoothly. I think low flow rates reported by some people are due to bubbles in the filter.