I have a 82 gallon flow through Quick Tank Q82V that is acting funny.
When the pump goes on it increases pressures it reaches max pressure on the switch and surges then shuts off around 5 psi less than the pressure switch.

It currently holds pressure but over time it dissipates. It also requires the pump to kick on when you flush a toilet or get water from the dispenser on the fridge.
I cannot tip the tank over it is very heavy.

I have a Franklin Controller
Pressure control switch set at 40/65
1/2 hp gould pump with 410 feet of drop

I assume my tank went bad based on the symptoms but not sure.

What should I replace the tank with?