I have a new steel wall pool with a vinyl liner inside a greenhouse. We used it since May and have used a combination of Trichlor and Bleach. Total of 3200 grams of Trichlor. PoolMath says for a 45000 L pool it should have a CYA level of 39. The water stayed perfectly clear. I was very busy for 2 weeks 2 months ago and was not able to test every day. I had been maintaining it at 2-4 ppm chlorine. Some extra people were swimming in the pool as well. I noticed some green coloration to the water about 6 weeks ago. I added 11.2 L of 10.8% bleach to shock the pool August 16-19. Vacuumed it several times and then noticed it was green again. I added 3.6 L of 10.8% bleach on August 28 and 14.4 L of 10.8% bleach on September 7. I estimated over 48 ppm of Chlorine at that time since it started at 8 ppm. I checked the CYA level with my kit but it was not that clear what the level was. It should be a little less than 39 because I added 1000 L of water at least 3 or 4 times. Since then the chlorine level has slowly been coming down. It is at 8 today. I still need to vacuum it every few days and the bottom looks just as green as before. The pH is at 7.6, the temperature is 22-24 C. Is there something else I can do? My alkalinity is always a little high at 180 but before the algae came into the pool it was clear for 3.5 months with kids swimming in it every day. My pool came with numerous chemicals, algicides and clarifiers and non-chlorine shock. I have not used any of them and it was working very well. Any ideas for what to do next. I would like to put it up for the winter in good condition.