Folks this is a first time post from a 1 month 1st time pool owner. Have a 31000 gallon chlorine pool that has white plaster. After 1 month we had the pool drained and light acid washed to remove some of the curing stains we couldn't get rid of. 3 days ago we started filling the pool and it took 52 hours after the light acid wash. At that point I started up the pump added about 5 lbs of shock and brushed the pool. The water from the tap had a greenish tint to it when we filled it. The next morning the water was still green although lighter. I backwashed the filter twice and added a total of 10 lbs of shock today and brush and vacuumed it twice. But in the deep end and in various place In the pool there are what appears to be green stains that I can't get to move. Water is crystal clear blue but how do I get rid of these stains?