Pool Filter Sizes Explained: How to Pick the Right One for Your Northern California Pool
When Lisa moved into her new home in Loomis, she inherited a sparkling backyard pool. But by the end of her first summer, the water looked cloudy no matter how many chemicals she added. The problem wasn’t her chlorine. It wasn’t her pump. It was her pool filter—too small for the size of her pool.
This mistake is more common than most people think. The wrong filter size forces your system to work harder, burns more energy, and leaves you battling algae and cloudy water all season long. Choosing the right filter isn’t just about keeping water clean—it’s about saving money and protecting your investment.
Why Filter Size Matters
Pool filters are measured in surface area and flow rate. If your filter is undersized, it won’t capture debris efficiently. If it’s oversized, you may waste money on equipment you don’t need. The goal is to match your pool’s volume and pump output with a filter that can handle the workload.
Common Signs of the Wrong Size Filter
Water stays cloudy despite balanced chemicals
Frequent backwashing or cartridge cleaning
Algae growth that keeps returning
Pump pressure spikes regularly
Higher-than-expected energy bills
The Three Main Types of Pool Filters
Before talking size, you need to know which type of filter you’re working with:
Sand Filters
Great for larger pools, especially in areas like Rocklin or Granite Bay where dust and debris blow in during summer. They’re durable and affordable but not as precise as other filters.
Cartridge Filters
Popular with homeowners in Roseville and Lincoln who want clearer water and less maintenance. Cartridges catch finer debris but must be cleaned more often.
DE (Diatomaceous Earth) Filters
The gold standard for crystal-clear water. These filters trap the smallest particles, but they require more care and higher upfront costs.
How to Choose the Right Filter Size
When sizing a filter, two numbers matter:
Gallons in your pool: Calculate by length × width × depth × 7.5 (for rectangular pools).
Flow rate from your pump: Measured in gallons per minute (GPM).
Once you know these, your pool service professional can recommend the right filter surface area for your setup.
Why Local Pools Have Special Challenges
In Northern California, heat, wildfire ash, and dust mean filters work overtime. If your filter is borderline too small, expect to clean it constantly. Oversizing slightly can make maintenance easier without sacrificing efficiency.
Ready for a Filter Check-Up?
If you’ve been struggling with cloudy water, backwashing too often, or climbing bills, your filter might be the culprit. At American Dream Pool & Spa Service, we help homeowners in Lincoln, Rocklin, Roseville, Granite Bay, Loomis, and Sheridan pick the right filter size and keep it performing year-round.
Contact us today to schedule a pool service visit—we’ll make sure your water stays sparkling, your equipment runs smoothly, and your backyard is ready for the next swim.
American Dream Pool and Spa Service is a trusted provider of pool and spa maintenance, repair, and cleaning services. They serve the areas of Lincoln, Rocklin, Roseville, Granite Bay, and Sheridan, CA, offering comprehensive care for both residential and commercial pools. Their services include everything from routine maintenance to specialized repairs for pool and spa equipment, ensuring that every pool owner enjoys a clean, safe, and well-maintained pool or spa throughout the year. With a focus on customer satisfaction, American Dream Pool and Spa Service strives to keep pools in top condition, regardless of the season.
