Retention tank is used for mixing different chemicals to give them enough time to mix properly. Where a bladder tank has air pressure in the bladder. Tank volume varies with water pressure to give a buffer with the volume of pressurised water in a system so pump doesn't short cycle.
Thank you for your reply. Yes, I am aware of the purpose of the retention tank.
Currently the well system consists of a 2 wire 1HP red rocket pump 150 feet down a well tied to a generator. The entire system was damaged in a fire. So, I am rebuilding it from scratch and found the fiberglass UT120 used for $100.
The tank is fiberglass, and I am aware that they will not tolerate negative pressure. So, a negative pressure valve is required. Otherwise, my understanding is that the UT120 can function as a bladderless pressure tank. That being said, I have also read about galvanized tank systems using avc control. I know that Pentair makes a UT120 that has an available avc adapter. I assume that I could add an avc controller to my tank, but it seems that to do so involves more than just adding a part to the system. Somehow, air needs to be introduced into the flow. The other option is to manage the air in the system manually. I cannot find much online about do this. So, any input/ advice is appreciated.
I am open to any and all suggestions, pros and cons of a bladderless system versus a bladder system. I could always buy a small pressure tank and feed it into the retention tank if it would make my life easier.