How to Backwash Cartridge Pool Filter - Complete Guide

Tools & Supplies Needed

Find on Amazon: Pool Filter Cartridge Cleaner , Replacement Pool Filter Cartridge , Filter Cartridge Storage Rack

Quick Answer

First, let's diagnose the issue: cartridge pool filters cannot be backwashed. Unlike sand or diatomaceous earth (DE) filters, cartridge filters don't have a backwash valve or multiport valve system. The term "backwashing" specifically refers to reversing water flow through sand and DE filters to flush out trapped debris. Cartridge filters work differently and require manual removal and cleaning.

Understanding Cartridge Filter Systems

Cartridge filters use pleated fabric or paper-like material to trap debris and contaminants. Water flows through the cartridge material from outside to inside, with particles getting caught in the pleated surface. This design makes them highly effective at filtering small particles (down to 10-15 microns), but it also means they can't be cleaned by reversing water flow like other filter types.

The confusion often arises because many pool owners are familiar with sand filters that have a multiport valve with a "backwash" setting. If you're looking to clean your cartridge filter, you'll need to follow a completely different process.

Proper Cartridge Filter Cleaning Process

Step 1: System Shutdown and Safety

1. Turn off your pool pump and filtration system completely
2. Turn off power at the circuit breaker for added safety
3. Allow the system to depressurize for at least 10 minutes
4. Never attempt to remove cartridges while the system is running

Step 2: Remove the Cartridge

1. Locate your filter housing (usually a large cylindrical tank)
2. Remove the top lid or unscrew the housing clamp
3. Carefully lift out the cartridge filter(s) - most systems have 1-4 cartridges
4. Note the orientation of the cartridges for proper reinstallation

Step 3: Initial Debris Removal

1. Use a garden hose with good pressure to spray between the pleats
2. Work from top to bottom, rotating the cartridge as you spray
3. Hold the nozzle at a 45-degree angle to effectively reach between pleats
4. Continue until water runs clear from the cartridge

Step 4: Deep Cleaning (Monthly or Bi-monthly)

1. Prepare a cleaning solution using cartridge filter cleaner or muriatic acid
2. For commercial cleaners: Follow manufacturer's dilution instructions
3. For muriatic acid: Mix 1 part acid to 20 parts water (always add acid to water, never water to acid)
4. Soak cartridges for 4-8 hours or overnight
5. After soaking, rinse thoroughly with clean water until no chemical smell remains
6. Allow cartridges to dry completely before reinstalling

Rotation System for Optimal Performance

Professional pool technicians recommend using a rotation system with multiple sets of cartridges. Purchase 2-3 sets of cartridges and rotate them every 2-4 weeks. This allows you to:

• Keep your pool running while cleaning cartridges
• Extend the life of each cartridge through proper drying time
• Maintain consistent filtration without downtime
• Ensure thorough cleaning without rushing the process

Signs Your Cartridge Needs Attention

Monitor these indicators to determine when cleaning is necessary:

• Increased pressure on your system's pressure gauge (8-10 PSI above clean pressure)
• Reduced water flow from return jets
• Cloudy or hazy pool water despite proper chemical balance
• Visible debris accumulation on cartridge pleats
• Pool struggling to maintain clear water after chemical adjustments

When to Replace vs. Clean

Cartridge filters have a finite lifespan and cannot be cleaned indefinitely. Replace cartridges when you notice:

• Pleats becoming permanently stained or discolored
• Fabric showing signs of wear, fraying, or damage
• Cleaning cycles becoming more frequent (weekly instead of bi-weekly)
• Filter failing to achieve proper flow even when clean
• End caps cracking or separating from the filter media

Quality cartridge filters typically last 6-12 months with proper care and regular cleaning. Higher-end cartridges may last longer, while budget options might need replacement sooner.

Maintenance Tips for Longer Filter Life

Maximize your cartridge filter investment with these practices:

• Maintain proper pool chemistry to reduce filter workload
• Keep free chlorine levels between 1-3 ppm based on your CYA levels
• Maintain pH between 7.4-7.6 to prevent calcium buildup on filters
• Use a pool skimmer and brush regularly to remove debris before it reaches the filter
• Consider a pre-filter or skimmer sock to catch larger debris
• Store clean, dry cartridges in a clean, covered area

Troubleshooting Common Issues

If your pool isn't clearing up after cartridge cleaning, consider these factors:

• Check if cartridges are properly seated and oriented in the housing
• Verify all O-rings and seals are in good condition
• Ensure the filter housing lid is properly tightened
• Test your pool chemistry - poor water balance can overwhelm any filter
• Consider if your cartridge size is appropriate for your pool volume and bather load

Remember, while cartridge filters can't be backwashed like sand filters, they offer excellent filtration when properly maintained. The key is establishing a regular cleaning routine and having backup cartridges available to minimize pool downtime.