Bowsmith 6036 SL220 Red NonStop® Drip Emitters SL200 Series 2.0 GPH Flow Rate. For over 40 years, millions of Bowsmith NonStop emitters have demonstrated that the unique NonStop Continuous Flushing Action (Pressure Cascade Principle) really works, even under conditions that would quickly clog ordinary emitters. With only 30-mesh filtration, Bowsmith NonStop emitters have operated successfully with water containing heavy concentrations of sand, silt, iron bacteria "slime", calcium carbonates, even algae and moss.