I need to replace my hot water tank as it's old and we run out of hot water fast. I actually did maintenance on it by shutting power off, cut off cold water and draining a bit of water from bottom drain as the maintenance manual says ro do every year, previous owner never did that, doubt many do.
Now the drain valve continuously drips and will not stop, super!
My questions however is that I can see the previous installer, plumber hopefully, added a hardening compound at the top of the cold and hot water. I can chip away at it, and it crumbles, but I do not know what this is and trying to unscrew with a wrench hard enough does not make them move at all. So I'm stuck. Here are images. Should I attempt with a bigger wrench to loosen these up, as the bond will break? or better off removing the pex piping by the metal rings that is holding the pex to the big screws. Sorry I do not know the name of these rings...

