Swimming pool sandfilter operation | What is the Multi-port valve?

Published by Admin on July 15th, 2011

The selector options on MPV (Multi-port valve) of a swimming pool’s sandfilter explained

The multiport valve is the main flow control valve on a swimming pool sandfilter, the most used filtration system in South Africa. The MPV has 6 settings to direct the flow of water from the swimming pool through the pump and filter.


Aquaswim swimming pool sandfilter










The MPV settings and their function are as follow:

  1. Filter
    The normal setting for the valve. Pool water is drawn through the pump, passed into the top of the filter tank and down through the filter media, via the filter underdrain system, after which it is returned to the swimming pool.
  2. Backwash
    The setting used for flushing out the filter when it becomes overloaded with dirt. Water is drawn from the pool by the pump and enters the filter through the underdrain system in the bottom of the tank, where it loosens the media bed and forces the trapped dirt upwards and outwards through the distributor in the top of the filtertank and away to waste, so you lose water from the pool. The filter media is retained in the tank. In this position the filtermedium or sand gets washed from the bottom upwards.
  3. Rinse
    Used to flush out any dirt trapped in the pipelines after backwashing, only required for a shorter period. The water follows the same path as when on “ FILTER” except that the water exits to waste instead of returning to the swimming pool. In this position the filtermedium or sand gets washed from the top downwards.
  4. Bypass
    Allows pump to circulate pool water without passing it through filter tank. Allows the heating and chemical dosing equipment to remain in use if filter tank is out of operation or when a chemical need to be mixed into the pool water without entering the filter.
  5. Waste
    Runs water from pool direct to the drain. Used when lowering pool water level, such as after heavy rain or when vacuuming a heavily contaminated pool without overloading the filter media bed.
  6. Closed
    Use this only when the pump is switched off. This position is used where filtration equipment is sited below pool water level. Allows pump lid to be removed and pump basket to be cleaned, provided that all pump suction valves are also shut off.


Sand filter Multi-port Valve

Please note that the swimming pool pump must always be swiitched off before selecting another position on the multiport valve.  Otherwise, it will create some excessive wear on the wagon wheel gasket and the filter may start to leak water out the waste-pipe when in the “Filter” position.


Sand filter wagan wheel gasket

If you need any help with fault-finding or want to ask a question, call Tel. 0861 012 012 or book a pool expert

Swemgat swimming pool experts

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