What is wrong with my pressure tank

First, I have a 20 gallon Jacuzzi Aqua P.O.D water pressure tank ( bladder type) factory set at 28 PSI. Recently I started to notice "swings" in my water pressure via taps, shower, toilets etc. The pressure would be normal but then would drop noticeably low and you could also see this on the pressure gauge next to the pressure switch. The pressure switch is a 30 psi (cut -in), 50 psi (cut-out). There would be a rapid rise and fall. Over time this got worse where the water pressure would be completely lost when I flushed the toilet +/- another tap running. To start the troubleshooting I had general maintanence done to my water softener system ( which was fairly clogged with iron sediment) but this did not change what I was observing.
My pressure switch was developing some rust so I changed that but this also did not change what I was observing. I was then told to check the air pressure in the water tank and I did it the correct way ( which has been described many times in this forum) which produced close to 50 PSI( up from the factory preset 28psi). I bled the air pressure back down to 28 psi and my water worked as it normally has done in the past. I did this "bleeding" in the morning but in 24 hours the air pressure in the water tank again increased to 45 psi one morning ( post water softener regeneration) and 35 psi (no water softener regeneration). Again, if I lower the air pressure in the water tank, everything is OK with my water. What is happening to the water tank?
Other useful info? The house, drilled well, old pressure switch and water tank are just over 5 years old and I have not had any water problems until the last couple of weeks.

Was the tank empty of water when you checked the pressure and got 50 psi?

If there is water in the tank, the air pressure will be equal to the water pressure.

Tell us the brand of the tank and the model #.

bob...

Before I measured the 50 psi, 45 psi and the 35 psi ( the different pressures I mentioned in my original message) I shut the power off to the water/ pump and turned on the water tap in my basement sink, which is where the tank/pump is also located. The water completely drains in about 30 seconds. I leave the tap "open" and then measure the air pressure in water tank. I then shut off the tap in the basement sink and manually start the water again. Have I measured the air pressure correctly? Thanks for your response.

Timm

Rock the tank to see if it feels heavy when your checking the pressure.

The water tank is a Jacuzzi P.O.D 2 with a model # ap-60/202. It is a 20 gallon tank which was pre-charged to 28 psi.

Just now, I rechecked the air pressure in the water tank and it measured 35 psi. It does seem on the heavy side with the water "drained" from the tank.

Timm

As noted earlier, the air pressure will be the same as the water pressure. It should go back down to the 28# if you drained the water without the pump running. Do you get any water out of the schrader valve (air valve)? If yes, then the bladder is shot. That tank size seems quite small, depending on the flow of the pump, it would probably cycle too much for longevity.

Sounds like water leaking slowly above- through the bladder and pressurizing the chamber above which has a [very slow] air leak.

If your tank sits overnight with pump off and the pressure equalizes then its fairly confirmed, also the weight when devoid of pump pressure is an important clue. What you called iron in your softener is likely rust and bacterial slime from the tank, I will never suffer another bladder tank again if I can help it.

When you replace it you might try a larger tank if you must continue with bladder [colon] tanks.