This is a system that I built to vacuum very dirty green algae pools without going through clients system. It consisted of a pool pump with a GFCI switch and heavy duty cord plugged into 110 outlet. The water is vacuumed through vacuum head on pole attached to a hose that is connected to the pump. It then goes through a cartridge filter and then a cyclone centrifuge that returns rather cleaner water to pool. The filter is taken out periodically to clean and the centrifuge has a lever on it to empty debris collected in bottom of unit. This worked extremely well on pools that were neglected throughout winter. The cyclone centrifuge can be plumbed into your regular system to improve water quality and cut down on water waste through backwashing.
It is a good idea to keep an eye on your pool pumps and other equipment during swimming season for any signs of leaking or loud noises that are not common. At the first sign of a pump leaking, it should be serviced by replacing the mechanical seal and any gaskets that are compromised. If the motor becomes very loud, there is a decision to be made. If pump is over 10 years old, I recommend replacing the pump as the newer ones run more efficiently. The motors can be replaced, which I do quite often, but labour is unpredictable on older pumps as they can be very difficult to disassemble.
Filters must be maintained to perform as they were designed to. There are sand filters and cartridge filters being used on pools today. They both need to be cleaned to maintain water quality. Cartridges should be taken out at least once a year to clean and should be replaced when water quality can no longer be maintained. You can figure on no more than 3 years for a set of filters. Sand should be replaced every 7 years or at some point where water quality cannot be maintained. Again if your sand filter is ancient, parts are not available for them and the entire unit should be replaced.