Sand (~3.0 sq ft), Cartridge (100–200 sq ft), DE (36 sq ft).
For a rectangular pool, use: Length × Width × Average Depth × 7.5 = Total Gallons .
Sand (~4.9 sq ft), Cartridge (400–500 sq ft), DE (60 sq ft). 3. Key Compatibility Checks
The three main types vary by their filtration precision (measured in microns) and maintenance needs. Filtration Level 20–40 microns Budget-friendly; low maintenance; lasts 5–8 years. Least precise; requires backwashing (wastes water). Cartridge 10–15 microns No backwashing; easier to install for above-ground pools. Cartridges need replacing every 1–2 years. D.E. (Diatomaceous Earth) 1–5 microns
A filter that is too small will overwork your pump and lead to cloudy water. As a rule of thumb, to reduce maintenance frequency.
