Keeping a swimming pool clean and clear requires consistent maintenance, and one of the most crucial components in this upkeep is the pool cartridge filter. These filters are known for their efficiency, ease of maintenance, and eco-friendly nature compared to other filter types. However, to ensure optimal performance and extended filter life, proper cleaning—including soaking—is essential.
This comprehensive guide explores everything you need to know about soaking pool cartridge filters, including the best cleaning solutions, recommended methods, and tips for effective maintenance.
Understanding Pool Cartridge Filters
Before delving into the soaking process, it’s important to understand how pool cartridge filters work. Unlike sand or diatomaceous earth (DE) filters, cartridge filters use a pleated polyester media that traps debris and contaminants as water passes through. These filters offer high surface area and exceptional filtration, typically capturing particles as small as 10–20 microns.
When the filter becomes clogged with dirt, pollen, oils, and other contaminants, water flow is reduced, which can lead to poor circulation and inefficient sanitation. Soaking the cartridges is a vital step in the cleaning process that helps remove deeply embedded debris and restores filtration efficiency.
Why Soaking Is Important
Simply rinsing a cartridge filter with a garden hose is often insufficient. Over time, oils, lotions, minerals, and fine particles can form a stubborn layer on the filter fabric. Soaking is a deeper cleaning method that breaks down and removes these built-up contaminants.
Regular soaking:
- Restores water flow and pressure
- Improves filtration efficiency
- Extends the life of the filter cartridges
- Reduces the frequency of replacements
- Helps maintain balanced pool chemistry
Failing to soak your filters regularly can lead to increased wear on the pump, cloudy water, and higher chemical consumption—as well as the potential for algae growth and poor water clarity.
Best Solutions for Soaking Pool Cartridge Filters
Not all cleaning solutions are created equal, and choosing the right one for soaking your cartridge filter is crucial. While some pool owners turn to household cleaners, using solutions specifically formulated for pool filter cleaning is highly recommended to avoid damaging the filter media and to ensure the removal of all contaminants.
1. Filter Cleaning Solutions
Commercial filter cleaning solutions are the most effective and safest way to soak cartridge filters. These products are designed to break down oils, grease, scale, and organic matter without harming the polyester or polyurethane components of the filter.
Examples include:
- Pool and spa filter degreasers
- Filter balancers (to dissolve minerals and metals)
- Enzyme-based cleaners (to break down organic contaminants)
When using commercial cleaners:
- Follow the manufacturer’s instructions for dilution
- Use a large container, such as a plastic 5-gallon bucket or a filter cleaning tank
- Allow the cartridges to soak for at least 6–12 hours
- Use a soft bristle brush for gentle scrubbing if needed
2. Bleach and Water Solution
A cost-effective alternative for sanitizing and cleaning is a bleach and water mixture. This method is primarily used to disinfect rather than remove oils and scale. Use unscented liquid bleach (sodium hypochlorite), typically at a 1:16 ratio (1 cup of bleach to 16 cups of water or 1 gallon of water to 1/2 gallon of bleach).
Warning: Bleach can be harsh on some filter fabrics, especially if soaked for extended periods. Always rinse thoroughly after this treatment and limit soaking time to no more than 1–2 hours.
3. Acid Washing (For Heavy Mineral Buildup)
If cartridges have significant scale buildup—especially in areas with hard water—a diluted acid solution may be required. This method should be used sparingly and with care.
Most commonly, professionals use:
- Muriatic acid (hydrochloric acid) diluted in water at a typical ratio of 1 part acid to 10 parts water
- Phosphoric acid–based cleaners as a less volatile alternative
Always add acid to water—not the other way around—to avoid dangerous chemical reactions. Submerge the cartridges for no longer than 15–30 minutes, then rinse thoroughly with fresh water until the smell of acid is gone.
4. Dish or Laundry Detergent (Temporary Solution)
In a pinch, mild liquid detergents (like dish soap) can be used to break down oils and greases. These are not as strong as dedicated filter cleaners but may offer a temporary solution.
Use a few drops in a gallon of water, soak the cartridges for 2–4 hours, and rinse completely afterward. Do not use detergents with degreasers or additives—these can clog filter media and be hard to rinse out.
5. Enzyme-Based Cleaners
Enzyme cleaners are a newer addition to pool maintenance and are gaining popularity for their ability to break down organic matter—such as body oils, lotions, and bather waste—without harsh chemicals. They can be used alone or in combination with regular filter cleaners.
These cleaners are most effective when used as a soak and should be applied regularly, not just during deep cleaning. They can help prolong the interval between deep cleanings and reduce the need for acid washes.
How to Properly Soak Cartridge Filters: Step-by-Step
Cleaning and soaking your pool cartridge filter may seem straightforward, but doing it right ensures the filter is thoroughly cleaned and ready to function efficiently. Here’s a step-by-step guide:
Step 1: Remove the Cartridges
Turn off the pool pump, depressurize the filter system by opening the air bleed valve, and remove the filter cartridges. Be gentle to avoid damaging the pleats or the end caps.
It’s a good idea to label the cartridges if you have multiple, so you can reinsert them in the same orientation each time.
Step 2: Rinse Off Surface Debris
Before soaking, give the cartridges a thorough rinse with a garden hose. Use a spray nozzle to reach between the pleats and remove loose debris like leaves, dirt, and sand.
This initial rinse reduces the workload on the soaking solution and helps the cleaner penetrate deeper layers of grime.
Step 3: Choose the Right Soaking Solution
Based on the condition of the filter and the contaminants present, choose the appropriate cleaning solution:
- Heavy scale buildup? Use a mild acid wash.
- Oily buildup from swimmers? Use a degreaser or enzyme-based cleaner.
- Algae or bacteria concerns? Use a diluted bleach or sanitizer.
Pre-mixed commercial cleaners offer convenience and safety by removing the guesswork of dilution and application guidelines.
Step 4: Soak the Cartridges
Place the cartridges in a large container—such as a 5-gallon bucket or a dedicated filter soaking tank. Add the cleaning solution according to dilution recommendations and allow them to soak for 6–12 hours or as instructed on the product label.
Occasionally agitate the cartridges by hand to help the solution penetrate deeper into the pleats.
Step 5: Light Scrubbing (If Needed)
For stubborn deposits, use a soft-bristled brush to gently scrub between the pleats. Avoid using a wire brush or anything abrasive, which can tear the filter media or flatten the pleats, reducing filtration effectiveness.
If the end caps are corroded or encrusted, clean those carefully without submerging the internal core of the cartridge.
Step 6: Rinse Thoroughly
Once soaking is complete, remove the cartridges and rinse them thoroughly with clean water. Make sure all traces of the cleaning solution are removed to prevent chemical damage to your pool water.
If you used bleach or acid, continue rinsing until the water runs completely clear and has no odor.
Step 7: Allow to Dry Before Reinstalling
While optional, allowing the cartridges to air dry before reinstalling can help spot damage, cracks, or loose seams. Never dry them in direct sunlight for extended periods, as UV exposure can degrade the material over time.
Ensure the cartridges are completely dry before storing or placing them back into the filter tank.
How Often Should You Soak Pool Cartridges?
The frequency of soaking depends on several factors including pool usage, water chemistry, and the surrounding environment. A general recommendation is to deep clean and soak cartridge filters every 4–6 weeks during the swimming season.
Additionally:
- Soak filters if you notice reduced water pressure or decreased filtration performance.
- Perform a mid-season deep cleaning in high-use periods.
- Soak after heavy pool parties or after periods of heavy algae blooms.
In areas with hard water or excessive organic debris (e.g., trees, pollen), more frequent soaking may be necessary.
Maintenance Tips for Optimal Filter Performance
Soaking is just one part of cartridge filter maintenance. To ensure longevity and peak performance, follow these additional maintenance tips:
Rinse Weekly
Between soakings, rinse the cartridges thoroughly with a hose weekly to clear away surface debris and maintain water flow.
Monitor Pool Chemistry
Imbalanced water chemistry can cause scale, metal stains, or biofilm buildup on the cartridge fabric. Regular testing and adjustment of pH (7.2–7.6), alkalinity, and sanitizer levels is essential.
Replace When Necessary
Despite regular cleaning, cartridges do wear out. Signs it’s time to replace your cartridges include:
- Cracked or separated end caps
- Collapsed pleats
- Persistent cloudy water even after cleaning
- Leaks or tears in the filter media
Most cartridge filters last 1–3 years with proper maintenance, depending on usage and care.
Store Properly During Off-Season
If your pool is closed for the winter or off-season, store the cartridges in a cool, dry place, preferably indoors, to avoid UV degradation, freezing, or moisture damage.
The Role of Water Chemistry in Cartridge Longevity
Your pool water chemistry plays a significant role in the condition of your filter cartridges. Let’s look at how chlorine, pH, and calcium hardness affect filters and what you can do to protect them.
Chlorine Levels
High levels of chlorine—especially from shocking the pool—can degrade the material of the filter cartridges over time. Prolonged exposure to high sanitizer levels can cause brittleness, tearing, and deterioration.
Maintain chlorine levels within the recommended range of 1–3 ppm to reduce chemical wear.
pH Balance
A high pH can reduce chlorine effectiveness and promote scaling, while a low pH causes aggressive water that can corrode metal components and deteriorate filter media over time.
Maintain a pH between 7.2 and 7.6 for healthy filtration and to protect both your equipment and the pool itself.
Calcium Hardness
High calcium hardness can lead to scale buildup on cartridges, especially in hard water areas. If the hardness is too low, pool water becomes corrosive.
The ideal range for calcium hardness is 200–400 ppm. Regular acid washes or calcium scale remover products may be necessary in areas with high mineral content.
Common Mistakes to Avoid When Soaking Cartridge Filters
Even experienced pool owners can sometimes make errors when cleaning filters. To get the most life and performance from your cartridges, avoid these common mistakes:
Using Dishwasher Tablets or Washing Machine Detergents
These products often include phosphates or highly concentrated chemicals that can clog or damage the filter media. Phosphates can feed algae and lead to increased chemical demand.
Over-Soaking or Using Too Strong a Solution
Leaving cartridges in cleaning solutions for too long can break down the bonds of the filter fabric or the end caps. Stick to the recommended soaking times and dilution ratios.
Reinstalling Before Proper Rinsing
Failure to rinse off all cleaning residue can introduce unwanted chemicals into the pool system, disrupting the water balance and potentially harming swimmers.
Reusing Old, Damaged, or Worn-Out Cartridges
Even with thorough soaking, cartridges that are physically damaged or aged will not filter efficiently. Replacing them when needed is key to optimal pool filtration.
Conclusion
Soaking pool cartridge filters is a vital step in pool maintenance that not only ensures crystal clear water but also extends the life of your equipment. Using the right cleaning solution, following proper soaking procedures, and maintaining good water chemistry are all part of a comprehensive maintenance strategy.
Whether you opt for commercial degreasers, bleach solutions, or enzyme-based cleaners, the goal remains the same: to restore the cartridge’s ability to trap debris and maintain optimal water flow. With regular care, your cartridge filter can continue to operate efficiently, keeping your pool sparkling clean and swim-ready throughout the season.
What is the best solution to soak pool cartridge filters in?
The best solution for soaking pool cartridge filters typically involves using a mixture of water and a specialized filter cleaner. These cleaners are formulated to break down oils, lotions, and mineral buildup without damaging the filter media. It’s important to follow the manufacturer’s instructions carefully to ensure proper dilution and soaking times, which can vary between products. Pool experts generally recommend using these commercial solutions for the most effective and safe cleaning process.
Alternatively, for mild cleaning or when commercial cleaners are unavailable, a diluted bleach solution (about 1 cup of bleach per 5 gallons of water) or a vinegar and water mix (1 part vinegar to 10 parts water) can be used. These alternatives are effective for addressing algae and light debris but may not be as potent for heavy buildup. Always rinse the filter thoroughly after soaking to remove any chemical residue before reinstalling it in the pool system.
How long should I soak my pool cartridge filter?
The recommended soaking time for a pool cartridge filter is typically between 8 to 12 hours, or overnight for best results. This duration allows the cleaning solution ample time to break down and dissolve oils, dirt, and other contaminants that have accumulated on the filter media. Follow the product label instructions for commercial filter cleaners, as some may require shorter or longer soaking periods depending on the formula’s strength and the level of buildup.
Soaking for less than the recommended time may not fully clean the filter, reducing its effectiveness and placing additional strain on your pool pump. On the other hand, soaking for too long, especially in bleach or acidic solutions, can potentially degrade the filter material over time. Therefore, it’s best to stick to the suggested soaking window and always rinse the filter thoroughly before reuse to ensure safety and longevity.
Can I use vinegar to clean my pool cartridge filter?
Yes, white vinegar can be an effective and affordable alternative for cleaning a pool cartridge filter, particularly when dealing with minor scale buildup and organic debris. To use vinegar, mix one part vinegar with ten parts water and submerge the filter in the solution for several hours or overnight. Vinegar is a mild acid, which helps to dissolve mineral deposits and kill algae or bacteria adhering to the filter fibers.
However, vinegar may not be sufficient for heavily soiled filters or those contaminated with oils and lotions from swimmers. In these cases, a commercial filter cleaner is a better option. After soaking the filter in vinegar, always rinse it thoroughly with clean water to remove any vinegar odor and prevent introducing unwanted chemicals into your pool system. Regular use of vinegar should be balanced with more intensive cleaning methods to maintain optimal filter performance.
Should I use bleach to soak my pool filter cartridge?
Bleach can be used to soak pool cartridge filters, especially as a disinfectant to kill algae and bacteria. A diluted bleach solution of one cup of bleach per 5 gallons of water is commonly recommended for this purpose. This method works well for routine maintenance cleaning or in emergency situations when commercial filter cleaners aren’t available. However, bleach should not be the primary or sole cleaning method for heavy organic or mineral buildup, as it does not effectively dissolve these substances.
It is crucial to avoid using bleach that contains any additives like fragrances or surfactants, as these can damage the filter material or leave harmful residues. After soaking, rinse the filter thoroughly to ensure no bleach remains. Overuse of bleach can shorten the lifespan of a cartridge filter by weakening the fibers over time. Therefore, it’s best used sparingly as part of a broader maintenance routine rather than a long-term cleaning solution.
What steps should I follow to properly clean a pool cartridge filter?
To properly clean a pool cartridge filter, start by turning off the pump and removing the filter from the housing. Perform a quick visual inspection to check for rips, tears, or major clogs that might require replacement or more extensive repair. Then, rinse the filter element with a garden hose to remove any loose debris. Avoid using a high-pressure nozzle, as it can damage the pleats or fibrous material of the filter.
After rinsing, soak the filter in a commercial cleaning solution or a homemade mixture (like vinegar or bleach and water) for 8–12 hours. Once soaked, rinse it again thoroughly to ensure all cleaning agents are removed. Allow the filter to air dry completely before reinstalling it in the system. Regular cleaning every few weeks, or as needed depending on pool usage, will improve filtration efficiency and reduce strain on your pool pump.
When should I replace my pool cartridge filter instead of cleaning it?
Pool cartridge filters can often be cleaned multiple times before needing replacement, but there are telltale signs that it’s time for a new one. If the filter’s media is torn, collapsed, or no longer holds its shape due to broken pleats, it’s time for a replacement. Also, if water flow remains sluggish or pressure gauge readings stay high after multiple cleanings, the filter may be too degraded to function properly.
Another key consideration is age. Most cartridge filters last between 1 to 3 years, depending on usage and maintenance habits. Even if the filter appears intact visually, diminished performance after proper cleaning is a sign to replace it. In addition, frequent clogging despite regular cleaning and water clarity issues in your pool can also indicate that the filter is no longer effective and should be replaced for optimal pool water quality.
Can I use muriatic acid to soak my pool cartridge filter?
Muriatic acid is a strong chemical and should be used with caution when cleaning pool cartridge filters. It’s effective at dissolving heavy mineral deposits and scale buildup when properly diluted. However, because it’s a powerful acid, it poses a risk of chemical burns and fume inhalation if not handled carefully. Use gloves and eye protection, and always add acid slowly to water—not the other way around.
Due to its potency, muriatic acid can also damage the cartridge material if left on too long or used at incorrect dilution ratios. After soaking, the filter must be rinsed extensively until the water runs clear and has a neutral pH. For safety and effectiveness, this method should only be used when dealing with severe scaling and not as a routine cleaning approach. Whenever possible, a less abrasive method, such as commercial filter soak or vinegar, is preferable for regular maintenance.