I have a 20+ year old WellMate WM-9 tank and an unknown depth submersible pump. The tank has a slow water leak at the top near the valve by the 2 white looking plastic retainers. I googled a replacement bladder (not sure if that is the problem) and it appears that it would cost nearly what a tank could be bought for. What info would be needed to determine which CSV and corresponding smaller tank size if I went that direction? There is 1" PVC from the well which is within 10 feet of the tank. Thanks