I am getting corrosion on my hot water tank connections that looks like electrolysis. I have a water purification system and it has been tested and working properly. I have a lightning protection ground wire that is connected to the copper piping that leads to the hot water tanks, Can this cause electrolysis?
Yep, that's electrolysis alright. Edwardt is right, you need a Dieletric Union to stop it & it should've been standard practice by whomever chose to do garbage work & guarantee a new water heater very prematurely.
That T & P valve on top might be shot too, which shouldn't be there anyway & was only used as an elbow. If it's from the same guy or firm that did the insulation, then find a new guy or firm...they're absolutely horrible & not even up to hack level work.