Pool pumps & sand filters compared

Cartridge filter pumps are compact and cheap. The water flows through a pleated filter cartridge, which you rinse regularly and replace every few weeks depending on how dirty it gets. They suit quick-up and smaller frame pools. Sand filters pump the water through a tank filled with filter sand or alternative media such as filter glass or filter balls. When the filter gets dirty, you simply backwash it via the multiport valve. For larger pools and long run times, sand filters are the more economical solution.

All the pool water should pass through the filter several times a day. As a rule of thumb, choose a system that circulates the pool volume once in about four to six hours. Example: a 12,000-litre pool needs an effective filter output of around 2,000 to 3,000 litres per hour. Manufacturer figures often state the maximum flow rate without resistance – in operation, with filter, hoses and height differences, it is much lower. So plan in some reserve.

In high summer, filter systems on above-ground pools usually run six to ten hours a day, spread over several intervals. An old rule of thumb says: water temperature divided by two gives the run time in hours. With heavy use, heat or after thunderstorms, more may be needed. With a time switch, run the pump during the day, when people are swimming and the sun encourages algae growth.

Backwashing is due when the pressure gauge reads well above the value after the last cleaning, or about once a week. After backwashing, run a short rinse so the sand settles.

Quartz sand of the recommended grain size is the classic filter medium and lasts several seasons. Filter glass filters more finely and clumps less. Filter balls are light and easy to handle but can't be backwashed – they have to be washed out instead. In winter, drain the pump and tank completely and store them frost-free.