How does a diatomaceous earth filter work?

Answer 1

Basically in a nutshell, diatamaceous earth is a very fine powder that is derived from ground up fossilized remains of extinct animals. Inside a d.e. filter(short for diatamaceous earth) it consist of devices we call grids. These grids can be various lenghths and widths depending upon the manufacturer. A common filter, for example, is a 48sq ft made by Pentair. In this particular set up, there are 7 full grids and one partial grid. Each grid is 24" high and is slightly curved. The width is about 10 to 12 " counting the roundness of the curve and 6 to 7 " for the partial grid. Each grid has a ribbed skeleton of plastic and is covered by a web of cloth, similar in consistancy with cheese cloth. The powder coats this cloth making each grid a filter in and of itself. The water is pushed thru this powder and cloth by the pump, goes into the inside of the grid and is forced out of the top of the grid thru a hole that is attached to what we call a manifold in the top of the filter. Then the water returns to the pool filtered. After a while of collecting dirt and debris you have to do a process called backwashing. You know its time to backwash when the pressure gauge reads too high. (consult the manufacturing specs on your system to know what that reading should be) When you backwash, you typically change a valve setting and let the system run for a couple of minutes then return the valve setting back to its normal filtration mode. ALWAYS shut off the pump each time you change the valve setting. In backwashing, it reverses the flow of water thru the grids and drives the dirt out of the filter thru a bottom drain built into the Plumbing. Most cities have ordinances that make the drain to be plumbed into your sewer system, however in some rural areas some people let it run out into the back yard. after backwashing you have to recharge the system with fresh d.e. This can be acomplished by taking a scoop or two of the powder and pouring it into your skimmer that is closest to the pump while the pump is running. What happens then is the d.e goes into the filter and recoats the grid with new, clean d.e pwder. Exactly how much d.e you put in, depends on the size of your specific filter.