Your filter is your last line of defense in trapping debris on a constant basis. That's why it's so important to use the right type and keep it operating as cleanly as possible.
This is basically a big canister of sand that helps trap smaller dirt and debris as water is forced through it. There are two types of sand filters used for pools. The most common is the high-rate sand filter, which uses sand as a filter medium. The other is called a rapid-rate sand filter, which needs layers of rock and gravel as a support for a top layer of sand.
As water passes through the sand bed, dirt and debris are trapped by sand grains. Sand filters use what's known as No. 20-grade silica sand, which is capable of trapping teeny-weenie 25- to 30-micron sized particles. (A micron is one millionth of a meter). Most sand filters have lateral tubes in the bottom of the tank instead of a solid underdrain. When filling a sand filter with sand, fill the empty tank with water about 1/3 of the way up first. This will help absorb the shock of the sand going into the tank.
Cartridge filters use replaceable paper or fabric-like pleated cartridges as their filter medium. Cartridges have a large surface volume to catch whatever the water pushes through them, and can trap 10- to 14-micron sized particles. Depending on the style you choose, a cartridge filter may have one or more cartridges inside the tank.
Diatomaceous Earth, which is composed of the skeletons of microscopic sea creatures, is the most effective, but also the most complex. DE filters not only remove the smallest particles (1 to 5 microns) of any filter, they actually sort of “polish” the water as it passes through it.
DE filters work by forcing water through the diatomaceous earth, then through a grid and back to your pool. These upright cylinder tanks have long half-moon, rectangular-shaped grids or fingers. A spreader, which is connected to a collector or manifold, separates these grids and holds them in place. Water flows into the tank, passes through the diatomaceous earth, through the filter grids, into the manifold and back into the pool.
Because the diatomaceous earth powder performs the actual filtering in both vertical and spin filters, you should never run water through a DE filter without diatomaceous earth in it for more than 1 1/2 minutes. This can permanently damage the grid.
First, you have to know when your filter needs cleaning. Take note of the pressure gauge on the filter. When it goes up to 10 pounds per square inch (PSI) above its normal operating level, it's usually a good time to clean your filter.
Reverse the flow of water by turning your regulator valve at the top of the tank to backwash. The backwash cycle should last until water passing through the site glass looks clean. Then turn the valve to the rinse position, and run this cycle for at least 30 seconds. When the filter is very dirty, it is good to repeat the process two or three times. Never turn the valve while the pump is running.
Unlike sand or DE filters, cartridge filters cannot be backwashed, and cartridges must be removed for cleaning. But the good news is cartridge filters are a breeze to clean. Simply remove the cartridge from the tank (with the pump off), take it out, hose it off, and soak it in Pinch A Penny's Filter Renew or Filter Clean for eight hours (or overnight). After soaking, spray and rinse it for about five to six minutes and put it back into the tank. We recommend keeping two cartridges so that you always have a clean one on hand while the other is soaking.
Clean your DE filter as you would a sand filter. But be sure to add new Diatomaceous Earth powder after each backwashing. To do this, mix DE powder in a bucket of water until it has a milky consistency, then slowly pour it through the skimmer while the pump is running. At the beginning of each season, disassemble the filter completely and clean the grids with Suncoast Filter Clean.
How your pool works is pretty simple, really. Water is drawn from your pool into equipment that filters out debris and often adds sanitizer or even heats it and returns it to your pool with the sparkle you're looking for.
To keep your pool it's healthiest, follow these easy pool care duties and you'll find keeping a perfect pool is one of your easiest household chores.