Your filter's flow rate (GPM) must be equal to or higher than your pump's output. For example, a 20,000-gallon pool with a pump turnover of 42 GPM requires a filter rated for at least 43 GPM. Capacity Chart:
Pool Filter Sizing - How to Choose the Right Size - Leslie's Pool Supplies buy pool filter
Premium filtration; catches tiny particles for "sparkling" water. Your filter's flow rate (GPM) must be equal
Sand (~3.0 sq ft), Cartridge (100–200 sq ft), DE (36 sq ft). Cartridge (100–200 sq ft)
A filter that is too small will overwork your pump and lead to cloudy water. As a rule of thumb, to reduce maintenance frequency.