We just replaced our pressure tank, check valve etc. The problem is that the gauge drops below the 30/50 and then eventually drops to 0 meaning we have total loss of water pressure. We checked the pressure in the tank. Its' at 28% which is the correct amount. We tried adjusting the pressure gauge and it did not help either. In fact we had to shut the pressure gauge off as it was allowing water to pump up past 60psi.

We are at a loss on this one. Also, we replaced the pump in May of this year. We do have iron in our water. Not sure what else to do with this one.

You replaced the tank, check valve and pressure gauge. What about the pressure switch.

The pressure gauge does nothing except show you what the tank pressure is. The switch is what turns the pump on and off. Once the pump turns off you should not loose pressure. If you do, the check valve is either not installed properly or is defective.

Once the pressure drops to 30# the pump should come back on. Remove the pressure switch cover and watch its action. When pressure reaches 50# you should see and hear the switch points open. When pressure drops to 30#, you should see and hear the switch points close. If that does not happen, turn off power, remove the switch and the small piping to it and make sure that it is not blocked by debris.

We tried adjusting the pressure gauge and it did not help either. In fact we had to shut the pressure gauge off as it was allowing water to pump up past 60psi.

I think you mean the pressure switch rather than gauge. If that is true, then it would seem that the switch is the culprit. A new 30/50 or 40/60 switch is about 25 bucks. Put in a new one.