A bad tank will cause your pump to cycle on and off rapidly while you are using water. If the pump is running continuously while water is being used, you probably have a leak or a pump problem, and not a tank problem. However, I never knew that particular tank to last very long either.
In the past, the larger the tank the better. This is no longer the case. At least for the last 15 years, I have been using a Cycle Stop Valve and a small tank instead of big tanks. Big tanks just slow down the cycling, a CSV eliminates cycling, and the tank can be very small. What most people are using now is a CSV with a tank as small as 4 gallon size to about a 20 gallon size.
Even an 80 gallon tank only holds about 25 gallons of water. Your pump has to be large enough to supply the amount of water you need. A tank is just to reduce cycling, not to store any water. So if you have a valve that eliminates cycling, you don't need a very big tank. The CSV and small tank will do things that a room full of big tanks cannot do.
See this link and let me know if you have any questions.