I don't see how that would replace my large well tank.
The large well tank keeps the well pump from running off/on cycles.
Do you have well or city water?
I have a well.
The kit comes with a pump for the well, the very small tank to replace the
very large tank, and a computer-control unit where you set the pressure,
mounted next to the small tank. I'd say the tank volume is about 1-2
gallons. The unit runs when water is in demand, and doesn't when there is
no demand. I can run the washing machine, take a shower, someone can flush
a toilet, and that warm shower water is hitting my back at a constant 70 psi
all the while.