Sizing is partially dependent on your environment and use (ex: if you have a lot of trees). At your pool size, you would likely at least want to look at a 400 s.f. cartridge filter if not bigger. You can also boost your effective capacity by adding a TJ16 Typhoon pre-filter. You can see the cartridges for this filter and other here: https://www.circupool.com/Replacement-Cartridges_c_54.html