MPV (Multi-Purpose Valves) are the big valves found on DE and sand filters. They do a number of functions as described below. Not all MPVs have all the modes listed.
An MPV valve is specific to a model filter and are usually not interchangeable.
MPVs on DE filters are mounted on the side. MPVs on sand filters may be mounted on the top or the side. Note that side mounted MPVs on DE and sand filter have the in and out pipes reversed - top in for sand filters and bottom in for DE filters. Make sure you have the correct MPV for your filter.
MPV Modes
Filter
Filter is the normal setting for the water to flow through the DE or sand.
Backwash
BACKWASH changes the water flow to wash water over the DE or sand and the dirt will flow out of the MPV waste line with pool water. DE will also be washed out of the filter and new DE will need to be loaded in after the backwashing is completed. A sand filter does not lose sand during a backwash.
Rinse
RINSE is done along with backwash. In DE filters you typically alternate between BACKWASH and RINSE modes three times during a backwash.
Recirculate
Use RECIRCULATE if you have a bad algae problem that is rapidly clogging the filter so you constantly need to backwash. Do the initial SLAM Process on RECIRCULATE until you kill much of the algae. Then filter out the dead algae without the algae continuously multiplying as you try and filter.
Or if you use Floc (that we don’t recommend doing) and intend to vacuum it to waste when it settles to the bottom of the pool. Run the filter in RECIRCULATE to not clog the filter with Floc or Clarifier.
Recirculate can be used when the filter is in need of repair - if you can't filter the water, at least you can circulate it
Waste
WASTE routes water directly to the waster line to dump water out of the pool.
Troubleshooting
MPV Repairs
- Spider Gasket
