I like this Camco Leak Detector Spray.
Only when the tank is full should you turn on the circuit breaker and send power to the heating elements.
Snugged up is good.
The water from this side of the tank is off and emptied so we won't have any real mess to speak of.
Just get it drained and stop.
Break it off with pliers.
It's really not that much you see.
As for compression and threaded fittings