I have tracked down my circuit breaker tripping due to the heater. Here is a picture of it. Should I replace the whole unit or just the element? Is there any way to check the element and how do I remove it? I will search the forums but if anyone can help it would be greatly appreciated. thanks

Sounds like you already did, the spa no longer tripps when it's disconnected.... bad element.

Removeal is just simply unscrewing it from the plastic housing. Replacement of the element only is all that is necessary.

By the way, there used to be a box on the back of that element, probably with the thermostat and high limit switch inside. It would appear that someone has removed these items.