There are 3 main types of swimming pool filters: Sand, Cartridge, and Diatomaceous Earth (D.E.).
Many filters installed in the 70’s and 80’s were much too small for the size of pool they filter, and with the deterioration of age are just barely operating. Many are difficult to service and do not backwash effectively. Newer filters that have not had regular service will not perform any better than an outdated or undersized filter, and can even cause bigger problems. Regular maintenance is the most important factor in continued performance and reliability.
The sand in a sand pool filter is specially graded to trap dirt particles. As a sand filter collects dirt its efficiency increases trapping even more dirt. When your pressure gauge shows a reading 8-10 lbs. over its clean, start-up reading, it is time to backwash (forcing water to flow through the filter backwards) the captured dirt out of the filter.
If your filter requires frequent backwashing (it should be able to operate continuously for a period of 4 weeks between backwashing), the sand may have deteriorated. A properly sized sand filter can go 5-7 years between sand changes. High amounts of oils from swimmers can gum up a sand bed over time. Years of a pump forcing water over the grains wear away the sharp edges of the sand. Worn sand becomes circular, and traps dirt less efficiently.
A clean cartridge pool filter element traps dirt and particles of 5 to 8 microns in size. During routine maintenance, the cartridge must be removed from the tank and washed thoroughly, top to bottom. The cartridge should be replaced every 5 to 7 years, depending on the work it was asked to do. Correctly sized cartridge filters can operate for 6 months between cleanings. The use of an enzyme additive is highly recommended for cartridge filters. This keeps the cartridge clean and free from oil build up.
We have had tremendous success with the cartridge filter shown. It is pretty much maintenance free. It is not uncommon for our customers to go the whole season without cleaning it. A down side of a cartridge filter is that if you vacuum slime or heavy dirt through it, then it will need to be cleaned. There is no backwash feature; however we do put in a bypass valve that would allow you to vacuum to waste without affecting the filter. No back washing = saving water, salt, chemicals and less work!
The DE pool filter is the most efficient type of pool filter. It can trap particles smaller than what the naked eye can see (4 to 5microns). As with sand filters, the pressure gauge indicates a need for backwashing when it reads 8-10 lbs. higher than its “clean” reading. After backwashing a DE filter, a new application of DE filter powder is added to the filter by pouring directly into the skimmer. A semi-annual breakdown of the filter is necessary to thoroughly clean DE filter grids.
A DE filter requires a coating of DE powder on the filter grids. This is where the dirt gets trapped in your filter. The powder, when first added, dissolves in the pipe on its way to the filter tank. When it reaches the grids, the powder stops coating the grid. The water passes on through the powder, then the fabric covered grid, leaving the dirt trapped in the DE powder coating. The use of an enzyme additive is recommended for D E filters. This keeps the grids clean and free from oil build up.
Improperly serviced DE filters may have pressure rise very quickly, and if left without proper DE coating, the grids will become damaged. A properly sized and serviced DE Filter should be able to operate continuously for a period of 4 weeks between backwashing.
The DE filter shown is a Quad DE from Pentair. It is fairly new and we have had great success with its performance and again we have chosen it because of its outstanding features. For high dirt areas and for people that like to suck up everything in the vacuum… this is a good choice. The DE grids are a made from a very tight, slick material that allows the DE to slump off when the system is turned off. When started, the DE essentially reorganizes and leaves the dirt in the bottom of the tank, significantly extending the intervals of backwashing. Occasional backwashing= less loss of water, salt and chemicals.