I currently have a AC pump (120V 2amp) that is generating alot of mains line noise. I would like to place a filter at the pumps plug but i'm not sure what would work best there.
The main reason I'm going this is the noise is making its way through a relay, over a optocoupler and into my arduino. It shows up as 2-4 volt swings on the arduino 5V rails when I power up or turn off the pump.