With a constant flow rate of 19.4GPM at a 15 psi drop, the Fleck 9100 is perfect for larger homes and light commercial applications. If there is a sudden demand for soft water suddenly spike, the second tank of softened water is used.The digital meter reads water usage electronically and during a power loss, NOVRAM provides valve status and memory backup. The Simple Electronics (SXT) control provides easy, step-by-step programming and an LED displays the time of day and soft water remaining.9000/9100/9500 Service Manual PDF 2.84MB