I have a vinyl lined above ground pool that holds about 23500 gallons with a sand filter. It was closed for the winter and since opened the water has been cloudy sometimes with a green tinge to it. I have spent hundreds on chlorine and other chemicals and cannot clear it up. We have scrubbed the pool and vacuumed several times. There is no debris. We have backwashed many, many times. These are my current readings fc 0.5, ph 7.2, ta 120, ch 250, cya 10. Last night I put in 4-182 oz bottles of 6% chlorine. This morning I am back at fc 0.5. I do this daily, after 2 hours the chlorine levels are a bit high, then within a few more hours the chlorine seems to be gone. What can I do? I had been using Granular 56 and Blast sold by the pool company until I found this site and 2 weeks ago began trying the bleach. But I'm still getting nowhere. My pool is less than a year old. I am hoping someone reading this site can help me!!! And I hope I have given all pertinent information.