Milky Blues

[pcgcpar3]

8 year old 17k above ground vinyl, well water. Always have had problems with shock turning water brown/green. Last year though we found the answer, nonchlorine shock, with chol tabs, worked great. This year opened to milk, raised water level and added metal out and stain out, pool guys: all levels are good accept chlorine levers (of course) shocked with 4lbs on Non-Chl shock and added algecide 60 with no change, one week later 2bls shock & turned water green milk, added super algecide and 5 lbs of another brand of non-chl shock and clairifier no change, added stain out and now back to blue milk. Is seems whatever the reaction that takes place is staining the liner and the stain out always does a good job of removing it but this time cant clear the water. Should I give up and hit it with reg shock and then treat the stain? Change the sand, its two years old? Help, No Mo Money lol.