So can you explain to us mere mortals how it is more efficient to use 3 or4 solenoids rather than just one? One sol also takes the air off of the pumps. This helps prevent stalling when you get 4 rainy days in a row and have older pumps.You do still have an issue with another solenoid to the bay that was running. The solenoid that's bad is only there to keep from wasting chemical if the others don't close properly.