The purpose of a pool cartridge filter is to clean your pool water by capturing debris and contaminants in the folds of the filter. With time these folds will become clogged, water will not flow thru the filter as easily, and pressure within the filter will increase. Operationally, with water flow down, you will not be turning you pool water as frequently and your pool contaminants will start to build up. It's time to clean your filter. As a general rule of thumb, your filter should be cleaned at least once a month during the summer and every other month if your pool is operational during the winter. This guide shows you how to replace multiple cartridges in a large Jandy CL580 Cartridge Filter. Although this guide is specific to the Jandy CL580 Cartridge Filter, many steps are common to other models of large cartridge filters.
RELIEVE PRESSURE - Next you will have to relieve the pressure that has built up in the pool filter. Note the pressure on the pressure gauge. It will typically read between 15 - 20 psi. To relieve pressure turn the air relief valve on top of the filter counter clockwise. Water will spray out initially as you see the pressure on the pressure gauge go to 0 psi.
CHECK PRESSURE GAUGE - Check the pressure gauge. As the pressure comes up, it will typically reads between 10 - 15 psi but this will vary according to the make of pool cartridge filter or its age. This value is your system's clean filter pressure. When the pressure is 8-10 psi higher, it's time to clean your pool filter again.