Just replaced a pressure tank with a hole in the bladder. While system was down also replaced the pressure switch. The switch is set at 50-70 psi and I thought the tank is at 46 psi. However, pump turns on raises pressure to 70 psi and turns off. As water is used it gets close to 50 psi then drops quickly and I lose water in lines. The pressure drops a few more pounds then pump kicks on and pumps back up to 70 psi and kicks off. My thought is I have too little pressure in the tank. Perhaps??

Set the tank pressure to 48# with pressure drained to zero by turning off the system and opening a low-level faucet.

I agree with John that tour tank should be charged with 48 PSI after the power is off and the pressure's bled off.

As water is used it gets close to 50 psi then drops quickly and I lose water in lines. Sounds like a faulty foot/check valve letting pressure slip away. Good luck, Tom