My pool is just a year old. water has been tested and everything is in line. but my pool liner has crystal clear appearance in the middle about 6 foot in diameter and the rest of the liner look greenish. the pool has been swept and brushed yet the blue/green outer part wont look like the middle of the pool
The greenish appearance could indicate algae. Have you tried an algaecide in addition to your chlorine to help to clear up the problem?