How Do You Know if Your Pool Filter Is Clogged? 5 Quick Tips

A clogged filter can cause all sorts of problems for your swimming pool. Whether you have a cartridge, sand, or diatomaceous earth filter, you should keep it running smoothly. Neglecting to clean and unclog the filter can lower your pump’s effectiveness, prevent debris from getting caught, and more.

To know if your pool filter is clogged, turn off the pump, check if the PSI is between 10 to 25, and open the filter chamber to clean it. If debris covers the cartridges, spray them until they’re clean. Diatomaceous earth should be sprayed and flushed, while sand filters need to be back washed.

In this post, we’ll talk about a handful of ways you can identify if your swimming pool’s filter is clogged, how you can clean various filter types, and how to maintain a good PSI. We’ll also discuss how to keep the impeller in good shape and when it’s time to replace your filter’s components.

How to Know if Your Swimming Pool’s Filter Is Clogged

Whether you’re worried because your pool pump is getting louder, the filter is indented, or the PSI is shooting through the roof, you’re in the right place. Your pool filter can’t remove debris if it’s clogged. Furthermore, it’ll prevent water from flowing through, which means you’ll have to deal with loads of algae and bacteria floating in the water.

Here’s a three-step process to know if your pool filter is clogged:

What PSI Should Your Pool Filter Be At?

According to Pool Research, your filter’s PSI should be between 10 to 25. For those of you who don’t know, PSI is a measurement of pressure. You can find the PSI on your pool filter by locating the meter on the top or side of the unit. It typically has a red or black hand on a white dial with numbers ranging from 0 to 60 or higher.

Cleaning your pool filter cartridges, sand, or DE (diatomaceous earth) will almost always bring the PSI back to the recommended range.

Inspect Your Filter’s Cartridges or Sand

Turn off the pool pump before trying any of these steps. If the cartridges are covered in debris, you should spray them gently with a hose until it’s all gone. Breaking the bands going around the cartridges makes them useless, so pay extra attention around these areas. Sand filters have to be back washed to remove the debris.

Check out this video guide on how to back wash a sand filter if you have one:

Check the Pool’s Inlets and Outlets

Put your hand over the inlet (where the basket is located on the side of the pool, not the pump) to feel if there’s enough suction. Your hand should be sucked up against the inlet fairly quickly if the pump is set to its highest mode. If it’s barely pulling, you likely have a clogged filter or a leak in the line. Try the same test over the outlets surround the pool’s walls. Again, there should be a good amount of pressure coming out of each of the outlets.

How to Clean a Clogged Pool Filter

If you know your filter is clogged, it’s time to fix the problem before it gets worse. A clogged pool filter leads to a loud pump operation, worse filtration, algae blooms, and more. The good news is it’s very easy to unclog your pool filter, and you can get it done in a matter of minutes.

So, how do you clean a clogged pool filter?

1. Turn off the pool pump to stop the water from moving. The PSI should drop to 0 right when you turn it off. If it’s not moving, you should replace your gauge. Try the Measureman 2-Inch Pool Filter Gauge. Make sure you choose the correct style (front vs. back).
2. Open the filter tank by untwisting the lock on the front of it. This might take some time, but don’t rush it; The outer ring will fall off if you don’t have a firm grip on it. You don’t need two people for the job, but it’d definitely make things a bit easier.
3. Remove the cartridge bracket from the top of the cartridges after you’ve taken off the tank’s lid. Some filters don’t have a bracket. Take out each filter, spray the tank until it’s clean and free of debris, then do the same to each of the cartridges. Most pool filters have between one to four cartridges.
4. Replace each clean, unclogged filter cartridge, then the bracket. Close the filter lid and ensure it’s snug, then tighten the outer ring and seal it with the bolt. You could use a socket wrench to make sure it’s tight enough to prevent it from leaking or flying off when the pump turns on.

When you’re done unclogging your pool filter cartridges, prime the pump. Pouring water into the pump’s basket until it’s full and doesn’t drain out, then seal the lid and turn on the pump. Once it’s primed, the PSI should return to normal.

Note: If you’re unsure what your filter’s PSI should be, check the manufacturer’s guidelines or look it up on the company’s website.

How Do You Know if Your Pool Filter Is Bad?

Sadly, not all pool filters can be fixed. If the filter won’t remove enough debris or the pump is barely moving water (and there’s no leak in the line or anywhere throughout the equipment pad and pipes), you might need to replace the cartridges, sand, DE, or DE fins.

I used to work at a reputable swimming pool supply store, and these are the primary ways we’d identify a bad pool filter:

• Broken or torn fabric on a DE or cartridge filter is an immediate sign they need to be replaced.
• Cracked or otherwise damaged filter tanks need to be replaced since they’ll leak water and reduce the pressure.
• Ripped bands surrounding the cartridge filter’s pleats are a major indicator that they should be switched with new cartridges.
• Leaky unions going into or out of the filter should either be replaced with new ones, have new O-rings, or lubricate said O-rings.
• If sand or DE is leaking into your pool, there was either a poor installation or something is damaged.

Any cracks or leaks found throughout your equipment pad will lower the pressure since water and air are escaping. Much like my article about fixing a vacuum that won’t suction, a clogged pool filter will limit or prevent suction and performance.

How Do You Know if Your Pool Impeller Is Clogged?

The impeller works in the opposite direction of a propeller. When the pump is turned on, the impeller’s job is to pull water through the inlet to the pump, then through the pipes and filter, heater, and other equipment you have, and back into the pool. If the impeller is clogged, none of this can happen.

Ironically, a clogged impeller has the opposite effect of a clogged filter on the PSI gauge. When the filter is clogged, the PSI will gradually climb to high levels. On the other hand, when a pool pump’s impeller is clogged, it can’t pull water, so the PSI can’t sense pressure and will stay low or at 0.

Most clogged impellers can be fixed by turning off the pump, unscrewing the front and back of the pump, and removing debris wrapped around the impeller. Common causes include tons of hair, leaves, grass, and other debris that finds its way into the pool.

In some cases, you can get away with turning off the pump, removing the lid and basket, then reaching your hand back into the pump and pulling out excess debris.

Note: If your pool pump is screeching, grinding, or won’t move, turn it off immediately and call a repair technician. A locked impeller can heat up and cause a fire or ruin the wiring, not to mention the expensive and irreparable damage it’ll cause to the pump.

In Conclusion

A clogged pool filter can cause issues ranging from limited flow to long-term, irreversible damage to all of your swimming pool equipment. We all know how pricey a new equipment pad can be, so it’s best to keep the PSI in the previously mentioned range and the filter cleaned.

Remember, the pool filter isn’t the only thing that can be clogged; The impeller, pump basket, inlets, outlets, and pool vacuum all need to be unclogged every now and then!