Hello, I try to fit as much anode into a tank as comfortably fits. I would stick a tape measure down into the anode port on the tank and measure to the top of the threads. Then I’d cut the rod at least an inch shorter than that measure; more if there was lots of sediment, which interferes with screwing the rod into place. The end of the rod doesn’t have to be really close to the bottom of the tank to work, so the standard 44″ rod is fine… two are finer! Hope that helps.