terryking228:
Hi,
These EMC problems are hard to debug!Here's some possible help from http://arduino-info.info
http://arduino-info.wikispaces.com/RelayIsolation
I think you need transient suppression across that solenoid coil. A MOV (Metal Oxide Varistor) would be good. A series combination of resistor-capacitor may work. Try .1 uf (rated at 400V or more) in series with 47 ohms to start...
Thanks for the links. I've tried a redlion suppressor module with the same values you mentioned, in the past and it didn't seem to help at all. The contactor with a suppressor on the coil seemed better, but the water solenoid wasn't phased by it.