How to Clean Your Pool Filter

If you’re battling an algae bloom in your pool, a lot of online and pool cleaning product instructions tell you to “clean your pool filter.” That’s all fine and well if you know how to do that, but what if you’ve never done it before? Well, here are the nuts and bolts of how to do it.

Now, your filter may be different in design, but the concept is the same, and you can apply what we discuss here to your pool filter.

Tools You’ll Need

You’ll need a wrench that matches the nut on the filter clamp, your garden hose, and a place to wash the filter down – preferably a lawn, so that the water from the hose returns to the aquifer.

Release Pressure in the Filter

Before you start, open the pressure valve at the top of the filter. You do it by simply turning the gauge counterclockwise until it stops. You’ll know it’s open by the hiss of rushing air.  Let it sit for about five minutes to make sure all of the air pressure is out of it.

Now turn off the main circuit breaker that powers the pool pump. You don’t want the pump to turn on when you have the filter open!

Remove Filter Cartridge

Remove the band clamp that holds the two halves together. Put your socket over the nut on the spring – you’ll see it there on the clamp – and turn it counterclockwise to remove it. It takes a lot of turns with the socket wrench, but it comes loose. Don’t lose the washer or spring nut from the clamp.

To remove the band clamp, tap the end of the screw back through its buckled. It may take a little prying to get the clamp off – try not to push against the filter’s fiberglass when you do that. Remove the clamp and set it aside.

Now, lift the top off the filter. You might need to wiggle it a little if it’s really stuck down. Pull it straight up and set it out of the way.

Once you’ve reached the green heart of the algae beast you can see how the filter system works. At the top is a plastic spider-like piece called the manifold. Water is pumped up through the supply tube and into the manifold. The manifold has up to eight outlets that force the water down through the inside of the filter panels. The algae gets trapped in the diatomaceous earth inside the filter panels instead of going back into the pool.

When the diatomaceous earth in the filter gets clogged up with algae it can’t hold any more, and lets it pass back into the pool. That’s how your water turns green.

The manifold will be marked with a couple of “lift here” handles.

Carefully lift the entire filter cartridge unit from filter tub. You may have to rock it back and forth a little to get it off of the supply tube. You can set the cartridge into a wheelbarrow, or simply carry it out to the lawn for the hosedown.

Before we go to the lawn, take a quick look at the supply tube. There should be a black O-ring near the top. If it’s not there, look around on the ground below, or feel inside the manifold to find it. It shouldn’t come off, but you don’t want to lose it. If it’s on the supply tube, that’s good.

Clean the Filter Panels

Once on the lawn, first we have to remove the manifold. One or two finger-tight nuts hold it in place. Remove the nuts, but don’t lose them. 

Gently twist and pull the manifold straight up off the filter elements. Now you can lift the filter panels off of the base plate.

Hose each panel down thoroughly, washing away as much of the colorful stuff as you can. They should be white. When you’ve finished with one panel, lean it upright with the open hole, which we’ll call the port, facing down so that the water inside can drain out. 

Don’t forget to hose off the base plate and the manifold, too. 

Reassemble the Filter Cartridge

Here comes the only challenging part of this endeavor: reassembly. It’s not hard, just challenging, like weaving with banana peels.

First, find the smallest filter panel – seven of the eight are identical, but one isn’t as wide.

There’s a spot on the base plate for that narrow panel It actually says something like “small element here.” With the open port pointing up, place the panel onto the base plate. It should want to stand up by itself.

Now, matching the curve of the panels with the swirls in the plastic base plate, mount each additional panel with the port pointing up. The central shaft of the panels should match to the round disk on the base plate. Keep going until you’ve gotten all eight panels mounted.

Here’s the monkey puzzle part: fit the manifold to the top of the ports. Start by putting the hump for the input pipe next to the narrow panel.

Gently, and I mean gently, work the panels around until the port in the top of each one fits into the mating hole in the manifold. It takes a lot of back and forth, but they will eventually line up.

Now, put the one or two retainer nuts back onto the posts to hold the manifold down. Don’t tighten them yet. Gently turn them down two or three revolutions, so that they aren’t coming off and provide a little bit of pressure.

One by one, gently push the manifold down over the top of each panel. Don’t push so hard that anything cracks of breaks. Gentle, even pressure is the key. You’ll see that the top of each port has a split so that it can bend a little. You want those splits to disappear inside the manifold port. If the slits remain exposed, water will squirt through there rather than down inside the panel, and the filter won’t work.

Keep working the manifold down until it sits firmly on top of all of the panels. Tighten the retainer nuts with your fingers until they are snug.

Reinstall the Filter Cartridge

Before you put the filter cartridge back into the filter, open the backflush valve and hose out the bottom bowl of the filter. Keep flushing it until it’s clean.

Lift the filter cartridge into the bowl, making sure that the end of the manifold fits over the supply tube. Push the manifold over the O-ring on the supply tube.

Close the backflush valve and fill the filter with water. This will reduce the amount of water that needs to come out of the pool to fill the filter.

There’s another O-ring, a big one, around the outside edge of the filter bowl. Examine it, looking for dirt or debris, rips or tears. If you find dirt, clean it off. If you find damage, replace it.

Use the hose to flush out the inside of the filter dome. 

Reassemble the Filter

Carefully place the filter dome onto the filter bowl. Turn the pressure gauge clockwise all the way – this closes the pressure valve. Now, turn the filter dome itself until the gauge is easy to see.

Fit the band clamp around the two halves of the filter assembly. Push the threaded retainer shaft through the receiver buckle and thread the spring nut onto the shaft.

Gently tap the clamp all the way around, driving it towards the buckle. Tighten the nut by hand, and tap around the outside of the clamp again.

Now use your socket wrench to tighten the nut on the band clamp. It will creak and groan as you tighten it. Pause after every tenth turn with the wrench to gently tap the perimeter of the band, driving any pockets of slackness towards the buckle.

You’ll know the clamp is tight enough when the coils of the spring touch other.

Power up the pump. You may need to prime it by adding water to the inline filter – that’s the one just ahead of the pump with the clear lid.

Congratulations! You did it!

Now read the post on How to Add Diatomaceous Earth to Your Pool Filter and you’ll be swimming in no time!

Please Note: Do not use this procedure if you are not certain that you can complete it safely, or if it does not seem accurate. Skippity Whistles provides this information as advice, and cannot accept any liability from your usage of it.


©2022 All right reserved


Published by John D Reinhart

Author, technical writer, videographer, actor, and naval historian John D Reinhart is a very busy guy. You can find his novels as

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