Swimming Pool Blog

Pool Filter Care & Cleaning

by Sean GriffinAugust 13, 2009




The three most common filters used in the swimming pool industry are sand filters, D.E. filters, and cartridge filters. All of these filters require a certain amount of maintenance and sometimes require replacement of certain parts. To get the most efficiency from your pool filter, follow a few simple guidelines for care and cleaning.

Typical pool filtration creates pressure within the filter as the water is forced pumped through the filter media. This pressure also affects the internals of your filter. Over sizing swimming pool pumps and/or allowing pressure to build too high can damage these components. Water chemistry can also weaken your filter components. Making sure your water chemistry is within the proper parameters, properly sizing your pump and filter, and backwashing system when necessary (typically 8-10 psi above start pressure) are the first steps in filter maintenance.

Cartridge filters utilize a paper element filter to filter out contaminants. Better brands are made of a product called Reemay or are spun polyester. As the filter operates, removing dirt from water being pushed through it, you eventually will need to remove and clean when dirty to continue to filter water properly. The cartridge can be cleaned using a garden hose with a good nozzle. A convenient way to clean is using the automatic cartridge cleaner called the Blaster. Take care when reassembling the tank to align both halves and secure the clamp band properly.

Staining can also become an issue with a filter cartridge. Using a chemical pool filter cleaner can help increase life of cartridge by removing clogging minerals and oils. Another trick is diluting muriatic acid; usually one to four parts acid to water, to help with mineral removal. Having a spare cartridge to rotate while cleaning is ideal. Over the years it will be necessary to periodically replace cartridges. Cleaning will become difficult and filter will become less effective. When you find yourself having to clean the cartridges twice as often as when they were new, it's time to replace.

Diatomaceous earth filters utilize a grid system which holds the filter media or D.E. powder. Once the D.E. becomes dirty, the pressure in the tank will increase and the powder will need to be flushed out and replaced. Typically this is achieved using a valve and reversing the flow of water through the filter tank. In theory all the dirty D.E. is flushed out, but from my experience, about 30% of the D.E. will remain in the filter. Over time your pressure will stay above your start up pressure due to D.E. stuck in between filter elements.

After backwashing, I like to replenish the DE powder with a smaller amount than on initial start-up, to account for the powder left behind. From time to time it is also recommended to manually clean your grid assembly, say every 6 months or 6 backwashes, whichever comes first. This can be achieved with a pressure nozzle and a garden hose. Sometimes it can be difficult to clean in between grids so they do have water wands on the market to assist you. When reassembling the tank, take care to align both tank halves and affix the clamp band properly.

The skeleton of the grid element, or plastic grids inside the material, can become damaged over time under constant pressure. The fabric like material that holds the media can also become stained and torn. In most cases replacing the damaged grid is necessary, although if you are handy with an awl, grids can be sewn. Eventually, however, the DE grids will need to be replaced.

Sand filters are also backwashed with a valve that reverses water flow through the tank, but the filter media (sand) remains in the filter while contaminants are flushed out. Over time the filter sand will need to be replaced. There is no exact timeline for changing out sand but typically it is every 5-7 years. The sand itself can become eroded and lose some of its filtering properties.

Sand filters are designed to push the water evenly through the sand bed and then return it to the pool. If the water creates channels through the sand bed you are losing effective filtration area. Another obstacle with sand filters is oily build up within sand filters, called mudballing. Mudballing is when the sand becomes clumpy and is not allowing water to filter through it properly. Calcification within a sand bed also decreases effective filtration area.If excessive mudballing or an excessive amount of calcification is within your sand filter it is time to change the sand, however, using a Filter Cleanse product can rejuvenate the pool filter sand.

When doing any maintenance work on your filter always take note of the condition of the other components. When changing out sand make sure you don’t need to swap out any laterals (and be careful not to break them). When you are cleaning your filter grids or cartridge make sure they are not torn or damaged. Damage can also occur over the winter season. Make sure to leave filtering elements in good condition during the months your pool is not in use.

In the snowbelt, service companies will clean the D.E. filter grids when they close down the pool for season, many times leaving them in the tank to protect them from damage. Remember that critters love to make homes out of a warm filter tank during the winter. Removing drain plugs is a must for draining and winterizing but I replace them, leaving slightly loose to allow water to escape and prevent those nasty critters from moving in and munching on your filter grids or cartridges.

Pool filters do a big job everyday. So give them a little TLC and they will return the love with years of service. For more info on swimming pool filters care and repair, see our pool filter info page.