Replacing your hot water tank can be a costly venture. Search the InspectApedia website. This was going to be a catastrophe. Solar heat for swimming pools is also discussed. Break it off with pliers. The mating surfaces must be cleaned thoroughly and covered with flux, the tubing cuts have to be absolutely square and the fittings can't be bent or distorted.
Remember to close the drain valve before turning on the water.
How to Install a Water Heater Yourself Quick and Simple (With Pictures)