I have a poured 10,000 gallon pool that was old when I bought this house 31 years ago. Service guys have told me it is a Lang pool. Since then it has had two coats of epoxy over the original marcite. There is a hollow spot in one area at the top and under the coping that needs to be repaired. What can I expect for repairs and resurfacing? I assume cement could be pumped into the hollow area. What would be the best trouble free and long lasting surface that is reasonably affordable? Any advice/recommendations would be appreciated.