My over flow has the baffle so it shouldnt lose syphon but my concern is a snail crawling inside the tube and restricting water flow. The water in the return chamber of my sump will go down causing the auto top off to kick in, filling my tank with fresh water while overflowing until the water reservior drains and the pump in my sump starts to run dry. I am not home for a few days at a time pretty often and cannot risk this happening. What are my options? I was thinking a float switch in the tank or the first chamber of the sump that could turn the pump off but that's expensive. I also thought a grate over the tank side of the overflow box but just another thing i gotta clean though seems like the better option. Any other ideas?