mg wrote:
Hello

I was getting about 5 gallons drawdown from my 8 year old 40 gallon
pressure tanks.

I have a 50' well. Recently, my water pressure started to go down to
nothing, and I noticed my untreated water looks green, not the usual
iron-brown color.

I decided to install a new pressure tank. I thought that solved the
problem...but no.

To regain water pressure, I turn on a faucet on and turn (on and off)
the incoming water valve (after the tank).

That works for awhile.

Any suggestions?

Although it is a common misconception, the water tank has absolutely
nothing to do with system pressure (unless it is totally waterlogged).
System pressure is set by the pressure switch.

In additon to what Stretch posted, a common cause of poor pressure is a
plugged water filter/softener. Others are corroded pipes, partly
closed valve, some crud partly blocking a fitting.

Harry K