So you’re facing issues with your pool filter, and you’re in need of some guidance. Well, you’ve come to the right place! Pool filter problems can manifest in various ways, and not all filtration issues are directly related to the filter itself. It’s essential to consider other factors that can affect filtration, such as clogged or closed skimmers, pumps, or valves. Before diving deep into troubleshooting your pool filter, check for any obstructions that could impede water flow to or from the filter. Below, you’ll find a comprehensive list of common pool filter problems along with potential solutions to resolve them.

10 Common Pool Filter Problems & How To Fix Them

#1 – Pool Filter Has No Pressure:

If the pressure gauge on your filter reads zero or close to zero when the pump is running and the valve is set to filter or backwash mode, there may be an issue. First, flick the gauge face with your fingernail to see if it pops up. Check for any warping on the gauge dial or face that may prevent it from moving. If the water is flowing normally through the filter but the pressure gauge is still not registering, the gauge itself may have failed or there could be a clog in the air bleeder assembly attached to the gauge. To investigate further, turn off the pump and use pliers or a small wrench to remove the pressure gauge. Insert a stick or small screwdriver into the hole to clear out any debris or clogs that may be blocking the pressure gauge or air relief assembly. It’s always a good idea to have a spare gauge on hand since they are relatively inexpensive and prone to eventual failure.

If the water is not moving through the filter at a normal rate, there is likely a clog or obstruction before the pool filter. Check for a clogged pump basket, impeller, pipe, or skimmer basket. Additionally, ensure that all valves before the pump are open and functioning properly. In some cases, the pump may have an air leak, causing it to draw in more air than water, which can decrease filter pressure and filtration efficiency.

#2 – Pool Filter Has Too Much Pressure:

If the pressure on your filter is higher than normal, it usually indicates a dirty pool filter. We generally recommend backwashing the filter or cleaning the cartridges when the pressure rises 8-10 PSI above the clean start-up pressure. Keep in mind that manufacturer recommendations may vary depending on the type of pool filter you have.

If the pressure is significantly higher than the recommended range, there may be foreign materials in the filter (such as paper products, plastics, mulch, or oils) that are causing severe clogging. Another possibility is a closed return valve or bypass valve after the filter, which can cause pressure to rise to dangerously high levels. It’s also worth checking for broken internal parts within the filter or the filter valve (multiport or slide) that may have become lodged in a pipe or fitting. Verify that all return-side valves or heater bypass valves are open, as pipes or valves after the filter do not typically clog with debris. However, broken filter or valve parts can restrict water flow after the filter, leading to increased filter pressure. If the pressure spikes unexpectedly to 40 PSI or higher, shut off the pump immediately as high filter pressure can be hazardous.

#3 – Pool Filter Pressure Rises Too Slowly:

Most pool filters will experience a gradual pressure increase of 5-8 PSI over several weeks. In larger filters paired with smaller pools, this process may take months. However, if your filter pressure rises slowly and it takes an extended period for the pool water to clear up, it suggests that water is bypassing the filter and returning to the pool unfiltered. This can be caused by problems with the filter valve, such as water bypassing in D.E. and sand filters. Internal issues inside the filter tank, such as broken, missing, or misaligned filter parts, can also result in water bypassing in all types of pool filters. Additionally, an oversized pool pump can push dirt directly through the filter, further contributing to slow pressure rise.

#4 – Pool Filter Pressure Rises Too Rapidly:

If your filter pressure rapidly increases within hours or days after backwashing, it indicates that the filter media (sand, cartridge, or D.E. grids) may require attention. If the media is clogged with oils or minerals, a deep cleaning with a pool filter cleaner specifically designed for your filter type is necessary. In some cases, you may need to replace the filter media entirely with new ones.

D.E. filters can also experience a rapid pressure increase when an insufficient amount of D.E. powder is used. Similarly, if you haven’t cleaned the D.E. grids thoroughly at least once per year, it can lead to a significant pressure rise. During periods of poor water conditions, daily backwashing or even more frequent cleaning might be necessary. However, under normal conditions with clean and clear water, a well-operating pool filter should ideally run for 3-6 weeks before requiring cleaning.

#5 – Pool Filter is Leaking Water Around Clamp:

For clamshell type pressurized pool filters, which include cartridge and D.E. filters, a leaking clamp band can be dangerous when pressure reaches high levels. To address this issue, start by turning off the pump and draining the filter tank by opening the air bleeder. Then, remove the filter clamp band and the filter o-ring (also known as the belly band o-ring). Clean the o-ring and the rim of the bottom tank where the o-ring sits, removing any dirt and debris. Inspect the o-ring for damage, such as being triangular instead of round or having cracks or dry rot. If the o-ring is compromised, replace it.

Apply Teflon pool lube to lubricate the filter o-ring, and reinstall the top half of the filter tank. Secure the clamp band around both tank halves and tighten the nut until the springs touch (for new-style clamps) or until the two ends of the clamp are within 1/4″ of each other (for older clamps). While tightening the clamp band, lightly tap it around the tank with a heavy wrench or mallet to improve the seal. In rare cases where the tank is warped and prevents a proper seal, consider contacting your dealer or the filter manufacturer for warranty coverage or replacement part options.

Pool Filtration: What You Need To Know About Pool Filters

#6 – Pool Filter is Blowing Dirt Back Into the Pool:

After backwashing, a small amount of dust blowing into the pool is normal. To address this issue, use the Rinse setting on the multiport valve for about 20 seconds to clear any remaining dust. In the case of sand filters, a small amount of fine, silty dirt passing through the filter continuously is considered normal. Using a filter cleaner or replacing the filter sand can help alleviate this issue, along with the use of a clarifier. To determine if the debris is sand, lightly brush it with a pool brush. If it poofs up into the water, it is dust. If it rolls around, it may indicate filter sand escaping through a broken filter lateral.

In the case of D.E. filters, the loss of D.E. powder into the pool, which appears as sandy dust, can occur due to small tears in the fabric, a loose filter grid assembly, cracks in the manifold, or a missing air bleeder screen or standpipe o-ring. Cartridge filters need to be properly installed in the tank to prevent water from bypassing the cartridge and flowing around it. Additionally, holes in the cartridge fabric can cause water bypass. Oversized pool pumps, improper use of cleaning chemicals, or aggressive cleaning with a pressure washer can also contribute to water bypass and debris entering the pool unfiltered.

Another possible cause for dirt blowing back into the pool is a faulty pool filter valve on sand or D.E. filters. If the valve is in need of repair or replacement, it may allow some water to bypass the filter and return to the pool without being filtered.

#7 – Pool Filter is Leaking Out of the Backwash Line:

If you notice water constantly draining or trickling out of the backwash line, the issue lies with the valve rather than the filter itself. In a multiport valve, the spider gasket and rotor work together to prevent water from flowing to the backwash port when the setting is anything other than Backwash. If you experience a continuous leak, open the multiport valve and inspect the gasket. Look for signs of twisting, deformation, cracking, or breakage. Additionally, if the valve handle feels loose and lacks tension, it may be necessary to replace the spring located under the handle.

#8 – Pool Filter is Not Clearing the Pool Water:

If your pool water remains cloudy despite proper water balance and sanitation levels, it’s essential to evaluate the performance of your pool filter. Firstly, ensure that the pump runs for a sufficient duration each day to allow the filter to adequately clean the water. Verify that both the pump and filter are appropriately sized for your pool and compatible with each other. There is a possibility that water is bypassing the filter, resulting in inadequate filtration.

If your pool filter is slightly undersized or if the filter media is worn out, using a clarifier can aid in coagulating suspended particles. Additionally, employing a flocculant can help settle suspended particles to the pool floor, allowing you to vacuum them to waste. In cases where poor water conditions persist for an extended period, replacing the filter media, such as sand, cartridges, D.E. grids, or D.E. powder, can significantly improve filtration effectiveness.

#9 – Pool Filter is Making Loud Noises:

While a pool filter typically operates quietly, noise originating from the equipment pad is often attributed to the pool pump rather than the filter. Loud pool pump noises are commonly caused by cavitation, which occurs when the pump is starved for water, or due to faulty internal motor bearings. Air leaks in the pump can introduce air bubbles into the filter, resulting in some noise as they pass through. To address this issue, inspect and repair any suction leaks before the pump using sealant. If you notice a constant stream of air bubbles in the pool or see bubbles through the clear pump lid, these are indications of air leaks.

#10 – Pool Filter Won’t Turn On:

It is important to note that the pool filter itself does not have a power supply, as it relies on the pool pump for operation. If your pool pump fails to turn on, several factors could be responsible. For detailed troubleshooting steps, please refer to our Pool Pump Troubleshooting Guide, which provides comprehensive information to address pump-related issues.

Remember, maintaining a properly functioning pool filter is essential for keeping your pool water clean, clear, and safe. Regular inspection, cleaning, and addressing any issues promptly will help ensure optimal filtration performance and extend the lifespan of your pool filter. By following the troubleshooting steps outlined in this guide, you can identify and resolve common pool filter problems effectively.

If you encounter any issues that you are unable to resolve on your own or if you require professional assistance, don’t hesitate to reach out to a qualified pool technician. They have the expertise and experience to diagnose and fix more complex filter problems.

Ultimately, prevention is key to avoiding pool filter problems. Regular maintenance, such as cleaning skimmer baskets, pump baskets, and backwashing or cleaning the filter media as recommended by the manufacturer, will help keep your pool filter in optimal condition. Additionally, maintaining proper water chemistry and circulation will minimize the likelihood of clogs and other filter-related issues.

With a well-functioning pool filter, you can enjoy crystal clear water and a refreshing swimming experience all season long.

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