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CHANGING OR RECHARGING YOUR POOL FILTER is a necessary part of pool maintenance, and is done at varying intervals depending on the type of filter you have.

Changing out a canister filter is an easy job that can be done by the average person in an hour or less, depending on whether you are throwing out the old filters or just cleaning them. You’ll want to make sure the pumps are off before you start. All canister style cartridge housings come apart more or less the same way – they are built in two halves with a top and a bottom, and mate in the middle with two flanges and a gasket. These halves are more often that not held together with a stainless steel or metal band that grips the edge of the flanges and holds the two halves together even while under pressure.

You’ll want to start be releasing the pressure inside the canister, which will make it easier to take the top half off. This is accomplished with a thumbscrew on top of the canister, usually by the pressure gage. Back this screw out and let the air out – you will hear a hissing sound. The next step in changing your filter is to undo the band that joins the top half to the bottom – a crescent wrench will be perfect to undo the single nut that usually holds these in place. Remove the band, and then pop the top half of the canister off and set it aside.

Having access to the actual cartridges, you can now change your pool filters. They are usually held in by friction to a tray on the bottom. Pop them out and inspect them. Note that your filters might not need to be changed, they might need only to be cleaned. You can hose them down, being careful to remove all surface debris. Some of them also can withstand pressure washing, albeit at a lower setting so as not to damage the element.

Changing your pool filters isn’t complete just yet – there is one important step most people neglect when doing this job. Before you put in replacement filters or filters you just cleaned, you need to clean the inside of the filter housing. Most filter housings have a sump on the bottom that can be drained using a plug or petcock on the bottom of the filter canister. This area, sometimes obscured by the filter tray has a shocking amount of sediment and debris within, and if you put new filters in without cleaning this area, you’re already shortening the interval for when you’ll have to do it again. Pull the square plug or open the petcock and hose out the canister, making sure the debris is eliminated. Also clean the inside of the top half as there is oftentimes a scum line inside there.

You’re now ready to insert your replacement filters, or the ones you hosed off. Ensure that they’re properly seated on the tray in the bottom and that the top tray that holds them all together is in place as well. Now is also the time to re0insert the drain plug or shut the petcock off.

Before you mount the lid and secure it, consider taking a garden hose and fill the bottom half of the canister with water. This will greatly relieve strain on the pool pump when it starts by having it not try to force air through the filters. Replace the top half of the canister and put the band back on. Most bands have a tension spring that keeps tension on the nut so that it doesn’t back itself off. It’s important that this spring’s coils are touching each other, which means the band is properly torqued down – this is a pressure vessel after all.

Start up the pool pump when complete, and let it build pressure. Leave the thumbscrew open at the top so that some of the excess air can be forced out, only closing it when the pump is solidly up and running.

Changing your pool filter should be accomplished every couple of years, while hosing down the filters and cleaning out the canister should be done once every six to eight months – which will keep your pool in tip top shape.

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