Water Pressure Issue at Tank

Have a 15 year old deep well system (~500ft). Latley the water pressure has been very sporadic. This morning I checked the bladder tank and it had 0 pressure when empty. I filled the tank to 30psi and restarted the well. The pump kicks off at 55psi but pressure goes to 0 before the pumps kicks on again. Since I drained the tank I am getting A TON of sediment in my whole house filter. Do I have a bad tank or is it the pressure switch. What's the best way to troubleshoot this?

Thanks

Assuming the cut in switch setting is higher than 30 psi, like 32 psi ... if it isn't that's your problem and you need to adjust the switch so the air pressure is 1-2 psi less than the cut in setting; which should be 31-32 psi (actually for the cut off of 55 psi, the air should be at 34-33 and the cut in at 35...

And if that's all correct, since the pressure falls to 0 before the pump comes on, your switch or the nipple or the hole the nipple screws into on the plumbing may be blocked causing the switch to not see the pressure fall in real time, and cause the switch to lag.

If that "whole house filter" is a disposable cartridge type, and it is before the switch (I think it is after the tank/switch but), it shouldn't be before the switch and probably is the cause of the switch lagging. You should never have anything that can block up between a submersible pump and its switch.