Shurflo Aqua King II Standard Fresh Water Pump To ensure long life and top marine plumbing system performance in all plumbing, SHURFLOs 4138 marine fresh water pump was designed with a unique over-molded single-piece diaphragm and internal by-pass. Additionally, the 4138 pump is constructed for smooth flow without rapid cycling. SHURFLOs reputation for quality has been built on the reliability and dependability of every pump they manufacture. Among the SHURFLO Aqua King II- 4138 fresh water auto