What is a simple way of reducing power to the element on the G30 to lower the temperature?
The G30 controller has a manual power control mode, which lets you set the heat output as a percentage of total heat (1600W).
You can set the heat output to e.g. 65% to use 1040W heating or 75% for 1200W.
To enter this mode, just hold the heat button on the control box for 6 seconds. See here for more controller instructions.