The diatomaceous earth filter for backwashing purposes operates on a similar principle to sand but will not require a pressure rise. The maximum pressure rise, usually 12-16 lbs is more important with this platform to avoid damage to the filter itself and early backwashing will not hurt the overall filter performance. It may be prudent, for example, to backwash the filter if the gauge has a 4 lb rise and the owners or pool service will be gone for several days.
The use of the multiport valve is identical to a sand filter; you must turn off the pump between each valve handle movement. The DE platform requires three two minute backwashes followed by rinse to clear, usually less than 30 seconds.
The backwash of a DE filter is designed to knock down all powder and contaminant from the grids and slapping (like the bottom side of a newborn infant) the side of the filter after each rinse cycle will yield optimum results as dirty powder drops to the bottom of the filter to be rinsed out.
Failure to get all used powder the bottom of the filter will not allow new powder to coat the grids evenly. At least twice per year the grids must be removed and soaked for trouble free performance. A one hour soak in five parts water, one part muriatic acid and 1 LB TSP (Trisodium Phosphate). It is usually a good idea to hire a pool professional if this is your first swimming pool on your first D/E filter.