I have a marquis sport 500 spa the I have set for 104 but only heats to 94. The top control says it's at 104 but I have a floating thermometer and it's saying 94. I'm at a lot on how to fix this any help would be great

I'd start by setting the temp. of the spa to 114 and see if that heats the spa up to 104 like you want...could simply be that the calibration of the thermostat is failing over time.

Mark

Spa electronics monitor the hot tub's functions, call for heat or circulation when needed, and more advanced control systems also provide error messages to help with troubleshooting a problem in case something goes wrong.