It is possible that it is not leaking now. If it is just slightly leaking in the morning, I will try tightening it a little more. If that doesn't work, I will take it apart, clean it, and reassemble with teflon and a bronze coupler. The previous steel tank lasted 16 years with no sign of corrosion at the copper fitting so maybe the steel (I assume steel) threads were coated with something so a bronze coupler isn't necessary. The threads should be good because copper doesn't rust and the tank is new. I only coated the male threads with compound and I put it on fairly thick. Then I screwed it into the copper fitting by hand until it was tight enough to require a wrench, which was at least three full turns later. After I got it tight with a wrench, I wiped the exposed male threads to see was what going on. Since then I got better wrenches and wrenched it tighter so the compound is being squished thicker at the intersection. I took photos of the back of the copper nut section and I see no cracks. One way or another, I will solve this problem without any TDPRI members flying out here.