A Clear Path to Sparkling Water: Mastering the Art of Filter Cleaning

Your pool's filter is the unsung hero of water clarity, constantly trapping dirt, debris, and microscopic impurities. Over time, these contaminants reduce water flow and strain the system, making proper cleaning essential for efficient filtration and clear water.

For sand and diatomaceous earth (DE) filters, backwashing is the standard cleaning method - reversing the water flow to flush out trapped particles. However, cartridge filters require a different approach, involving manual removal and rinsing.

In this guide, we'll explore how different filters work and provide step-by-step cleaning instructions tailored to each type.

Understanding Different Pool Filter Types

Not all filters operate the same way. While sand and DE filters use a backwash cycle, cartridge filters must be cleaned manually. Choosing the right method for your system is crucial for maintaining efficiency.

Sand Filters

  • Pool water passes through a bed of fine sand, which traps dirt and debris.
  • When pressure builds up (usually 8-10 psi above normal), backwashing reverses water flow to flush out trapped particles.
  • Simple and durable but requires periodic sand replacement every 3-5 years.

Diatomaceous Earth (DE) Filters

  • Uses a fine powder (DE) coated on filter grids to trap even microscopic contaminants.
  • Backwashing removes debris but also washes away some DE powder, requiring replenishment after each cleaning.
  • Filters more finely than sand, but requires careful DE disposal to meet environmental regulations.

Cartridge Filters

  • Consist of pleated fabric-like cartridges that trap debris without a backwash option.
  • Instead of reversing water flow, cartridges must be physically removed and cleaned.
  • Provides better water flow and energy efficiency, but requires manual maintenance every few weeks.

How to Backwash a Sand Filter

Sand filters rely on backwashing to clear out trapped debris. Follow these steps to restore proper water flow.

1. Turn Off the Pump
  • Always shut off the pump before changing valve settings to prevent damage to the system.
2. Set the Valve to "Backwash"
  • If your system has a multiport valve, rotate it to the "Backwash" setting.
  • For push-pull valves, follow the manufacturer's instructions to engage backwashing mode.
3. Start the Pump and Watch the Sight Glass
  • Turn the pump back on. Dirty water will flow out through the waste line.
  • Run for about 2-3 minutes, or until the water appears clear.
4. Rinse the System
  • Turn the pump off and set the valve to "Rinse".
  • Run for 30 seconds to settle the sand and prevent dirty water from re-entering the pool.
5. Return to Normal Filtration
  • Switch the valve back to "Filter", turn the pump on, and resume normal operation.

How to Backwash a DE Filter (With DE Powder Replacement)

Backwashing a DE filter follows similar steps but requires adding new DE powder afterward.

1. Turn Off the Pump
  • Always shut down the pump before adjusting the valve.
2. Set the Valve to "Backwash"
  • Engage the "Backwash" mode and restart the pump.
  • Allow dirty water to flow out for 2-3 minutes, or until it runs clear.
3. Turn Off the Pump and Reset the Valve
  • Switch the valve back to "Filter" mode.
4. Add Fresh DE Powder
  • Calculate how much DE powder is needed (refer to your filter manual).
  • With the pump running, slowly add the DE powder through the skimmer, allowing it to coat the filter grids.
  • If this step is skipped, the filter will lose efficiency.

How to Clean a Cartridge Filter (Non-Backwash System)

Cartridge filters do not use a backwash cycle - instead, the cartridges must be physically removed and cleaned. Proper maintenance ensures good water flow and maximum filter lifespan.

1. Turn Off the Pump
  • Always shut down the pump before opening the filter housing.
2. Release Air Pressure
  • Locate the air relief valve (usually on top of the filter tank).
  • Slowly open it to release trapped air and reduce pressure inside the system.
3. Remove the Filter Cartridges
  • Open the filter housing by loosening the locking mechanism or clamps.
  • Carefully lift out the cartridges, taking note of their position for reassembly.
4. Rinse the Cartridges with a Hose
  • Use a garden hose with a spray nozzle to wash off dirt and debris.
  • Aim the water between the pleats at multiple angles for a thorough clean.
  • Avoid using a pressure washer - it can damage the cartridge material.
5. Soak the Cartridges (If Needed)
  • If the filter is clogged with oils, sunscreen, or algae, soak it in a filter cleaning solution.
  • Mix the manufacturer-recommended cleaner with water in a large container.
  • Let the cartridges soak for a few hours or overnight, then rinse thoroughly.
6. Reassemble the Filter
  • Ensure the cartridges are fully dry before reinstalling.
  • Place them back in the housing, aligning them correctly.
  • Secure the filter housing and close the air relief valve.
7. Restart the System
  • Turn the pump back on.
  • Open the air relief valve briefly until water flows out steadily, then close it.
  • Check the pressure gauge to confirm proper operation.

Best Practices and Common Mistakes

Monitor the Pressure Gauge

Backwash or clean the filter when the pressure rises 8-10 psi above the normal range.

Don't Over-Backwash

Backwashing too frequently wastes water and can unbalance pool chemistry.

Dispose of DE Safely

DE powder should never be washed into storm drains - check local regulations for proper disposal.

Rotate Cartridge Filters

If possible, keep a spare set of cartridges to swap in while the dirty ones are soaking.

Track Your Cleaning Schedule

Keeping a log of backwash dates and PSI readings helps anticipate maintenance needs.

Cleaning your pool filter is one of the most critical maintenance tasks for keeping water clear and balanced. Whether your system requires backwashing (sand/DE filters) or manual cleaning (cartridge filters), regular maintenance ensures optimal performance and extends the lifespan of your filtration system. By following proper cleaning procedures and monitoring pressure levels, you'll keep your pool water sparkling and your equipment running smoothly all season long.

Are you ready to continue your pool water journey?

Download our app