Water pulsating at fixtures

Pressure in tank is 23psi, pump cut-in is 25psi and cut-out is 50 psi. Pump is kicking in and out about every 20 seconds or so with water running. When all water is off the pressure stabilizes. It may help you to know, I added a second mobile home and two frost free hydrants last summer. My pressure tank is only 20 gallons. Could the tank be the problem even though it just surfaced as an issue?
Thank you,
shogan65

Did you empty the water from the tank before you checked/adjusted the air pressure?

Is the pump a jet or submersible?

Doesn't matter what kind of pump he has, the tank is probably water logged.

If its a standard tank, shut the pump off, blow all the water out and put a precharge of air in it. The precharge should be a few pounds below cut in pressure.

If you have a diaphram or bladder tank, the diaphram or bladder has failed and the tank needs to be replaced.

Failure to address this condition will lead to premature pump failure.

Thank you, I am worried about premature pump failure. The tank is a diaphragm tank, about 20 years old, (unsure if that contributes to the issue), but thank you for your advice.

20 years is about the lifetime of a diaphram or bladder tank. I would highly recommend a Well X Trol replacement, the bigger the tank the better.

The bigger the tank the better because it reduces the number of on/off cycles. But there are ways to stop the cycling. Then a large tank is not needed.