← Back to Pool ToolkitTool: Filter Loading Rate

Pool Filter Velocity Calculator

Calculate filter loading rate and face velocity from flow and effective filter area.

Estimated result:
Planning estimate: Confirm equipment specifications, performance tables, warranties, local requirements, and site conditions before purchasing or changing equipment.

How This Calculator Works

Enter realistic values from your pool, equipment labels, utility bill, or written estimate. Change an assumption to see how it affects the result.

What Matters Most

Filter loading rate is flow divided by effective area. Water face velocity converts gallons per minute per square foot into feet per minute.

Compare the result with the filter manufacturer’s published design and maximum flow limits. Effective area is defined differently for sand beds, cartridges, and DE grids.

Common Mistakes

  • Using advertised maximums instead of performance at actual operating conditions.
  • Ignoring plumbing, filter, heater, sanitizer, automation, or electrical limits.
  • Rounding inputs before the final result.
  • Treating a planning estimate as a substitute for manufacturer instructions.

Frequently Asked Questions

Should I use measured values?

Yes. Measured flow, watts, pressure, dimensions, and current pricing usually improve the estimate.

Is the largest option always best?

No. Equipment should meet the required range without violating minimum flow, maximum flow, velocity, electrical, space, or compatibility limits.

Pool Gal Pro Tip 💦

Write down the clean, working baseline when equipment is new. Future-you will look brilliant when troubleshooting season arrives.