Choose 12VDC or 24DC Relays.
Zettler AZ755-1A-24DE (24V DC) / Omron G2R-1A-E
...and many others in Gecko / AEware / Balboa / Pentair / Hydroquip / SpaQuip
Pins spaced 7.5mm apart (Width), 5mm apart (Length), 20mm from coil pins to closest contact pins. The NC (normally closed) contacts can be cut off for most spa PCB applications.
Do Not Confuse With AC Relays!