We have purchased last year a holiday house in south of France. It came with a swimming pool (10X5X1.5m) - 75m3. The swimming pool is covered by a dome. The water was nice and clear when we bought the house, but sometime later, to my horror it turned into a green swamp. Last year I had no idea how to take care of the pool. Still, before the winter I treated the pool with chlorine, algaecide and 50g of copper sulfate and I adjusted the Ph from 8.2 to 7.2. I closed the pool for the winter and left it half empty. In spring we found the water clear but the pool had a substantial green-black mud on the bottom. Ph was 8.4. Since I was told by a neighbor that the water is saturated we decided to empty the pool and start with clean tap water. I have installed an 110W UV sterilization lamp on the return line and I dissolved to sets of 20 bromine tablets in the skimmers. I added some algaecide and a 50g dose of copper sulfate. Now the swimming pool is covered (75%) by an opaque plastic cover and by the dome. The water was only 15 deg when we left. I left the pump +UV lamp operating 12h per day. Two months later the water is still nice and clear. My neighbor added another 10 bromine tablets in the skimmer and adjusted Ph to 7.2. I hope to find the swimming pool with clear water. Any advice for the up keeping of the swimming pool will be appreciated.