Spa Doctor--GFCI Pops

In 99% of the time it's the heater when the gfci pops.

To confirm you can disconnect the heater from the loop. First thing is to turn off the MAIN POWER SWITCH.

To isolate the heater depends on which model you have but in general, ID the heater. The most common heater on Jacuzzi Hot Tubs are a "U" shaped steel tube outside the control box. Some models have the heater strapped to the back or bottom.

Once you ID the heater, remove the metal cover on the control box. You will find 2 wires from the heater to the board.

Once you disconnect the wires make sure they are not touching anything.

Turn ON Main power or GFCI breaker.

If the spa comes on, replace the heater.