How Good Is a Sand Pool Filter?

Microns

• A micron that is visible to the naked eye is sized at around 40 microns. Any filter that has the ability to trap something invisible to the naked eye is good at filtering pool water. Sand filters have the ability to trap dirt as small as 20 particles in size. The other major type of filter systems are cartridge and diatomaceous earth filters. The cartridge filter can only trap dirt as small as 25 microns. A dimatomaceous earth filter, however, is the most efficient on the market and can trap dirt and particles down to the three microns range.

Middle of the Pack

• Pool filter quality and effectiveness is measured in terms of filtering capabilities, which leaves the sand filter somewhere in the middle of the road between the diatomaceous earth and cartridge filter. The filter is responsible for trapping these particles of dirt and preventing them from reentering clean sanitized water. If these particles were to escape back into the water, they would give the swimming pool a cloudy appearance. All of these filters are sold on the market because they work. The choice is not about which is better, but rather which is better suited for you.

Sand Filter Functionality

• A sand filter is a tank filled with silica sand that traps the dirt and particles. The sand is stored inside laterals, which are tubular extensions from a central PVC core. Water passes through these laterals, which have porous screens at the end of each tubular extension to prevent the silica sand from entering the water. As the water passes through the laterals, it traps the dirt on its way through. The sand inside the filter actually becomes more effective as it becomes dirtier. Internal pressure is monitored by a pressure gauge.

Maintenance

• The pressure gauge indicates when the time has come to clean the filter. On average, about once per month, a sand filter will need to be backwashed, which is indicative when the pressure rises 8 to 10 pounds per square inch (psi) above its normal operating pressure. Backwashing is the process of reversing the water flow to clean the sand free of the dirt and particles. The sand inside the filter can last up to seven years before it needs replacement, which is a faster method of maintenance over a diatomaceous earth filter in which DE powder must be added regularly. Maintenance is also slightly easier than a cartridge filter as well, which must be partially disassembled to clean. The sand filter will provide for crystal clean water as long as it's backwashed when necessary and well maintained. Never ignore the pressure gauge, which tells you when it must be cleaned. Running a filter at high pressures can damage the laterals.