I have a small residential above ground pump. The previous owner had a 20G bladder tank and a non bladder, regular old steel tank connected to the system. I don't know why the steel tank was there unless he was trying to use it as a bladder tank. It was introducing rust into the system so I just turned off the valve and left it there. I realize I need to get this off the system. So I only have the 20G bladder tank. The pump runs for about 23 seconds in a cycle and the water pressure is pretty herky jerky. I understand it should run for about a minute. So I went down to Lowes to get another tank to add to the system. Lo and behold they have a bunch of 58G tanks marked down to $50. from $284. My lucky day. So now the question is, Should I add this 58G tank to the system making it 78G worth of air, or put the 58G on by itself because that would be enough? Is it a more-the-better situation?