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 s model filter and are usually not interchangeable.
MPV Modes
Filter
Backwash
Rinse
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
