There are three primary types of filters:

– Use sand to trap debris; easy to maintain and best for larger pools.

– Use a pleated cartridge; provide superior filtration and energy efficiency with minimal maintenance.

– Offer the finest filtration (down to 2-5 microns) by coating grids with DE powder; require more maintenance but deliver the cleanest water.

Each filter type has its pros and cons based on pool size, maintenance preference, and water clarity goals.

• Cartridge filters should be cleaned every 2–4 weeks and replaced every 1–2 years, depending on use.
• Sand filters typically require backwashing every few weeks and sand replacement every 5–7 years.
• DE filters need backwashing and DE powder recharge every 4–6 weeks, and full grid cleaning every few months.
  

Always follow the manufacturer’s recommendations and inspect your filter regularly to maintain peak performance.

Filter size depends on your pool’s gallons per minute (GPM) flow rate and total volume. A good rule of thumb is to choose a filter that can handle your pump’s flow rate and turn over your entire pool volume in 8–10 hours. Oversizing slightly is better than undersizing—it reduces strain on your pump and extends the filter’s lifespan.

Signs it’s time for a replacement include:

• Constantly dirty or cloudy water
• Decreased water pressure or poor circulation
• Cracked or damaged filter housing or cartridges
• Sand leaking into the pool (for sand filters)
• DE powder returning to the pool (for DE filters)
  
  Routine maintenance can extend filter life, but once you start seeing performance issues that cleaning won’t fix, it’s time to replace.