Probably, you don't. Assuming you are referring to a pressure tank and not a holding tank, let's address a few questions first.

1. Does your tank have an air valve at the top?
2. At what pressures does your pump cut on and cut off? You can check your pressure valve while you have a faucet running to find this out. You will likely be able to hear a "click" as the switch turns the pump on and off.
3. Turn on an outside faucet and see how long the water runs before the pump has to cut on to build pressure back up. Time it in seconds. Hopefully, it will be at least a minute.

Get back with your answers.