Active job

40+ year old concrete pool needs some TLC - relining/refurbishing

We have a large concrete pool that was put in around the late 70s. Currently it is tiled around the outside and painted inside. However, over the last 3 years, no amount of painting and repairing has done a good job so it is time to look at our options. It now has some cracks in the concrete and is generally looking very tired and sad. Only one of the lights work (at each end). We are interested in any ideas that can upgrade the pool so that it will last another 20+ years. We live in the country and the house is mid 70s so there is no point going too flashy so we want a practical solution. Re-plastering? A new surface of some kind? Ideally we would like the project completed before Christmas but open to discussing. Waiau Pa is about 20 minutes from Pukekohe and Papakura - FYI.