clear green water

Had been gone on vacation, when returned pool showed signs of alage and was light green (this was 2 weeks ago). I shocked and have continued to keep chlorine high to rid of the alage. But it just continues to stay a clear light green. I have had metals in the past, I do have to fill with well water and I do have a heater so when it would not clear I thought that might be the problem, so I added the product from Walmart to rid of metals. That did not work....still clear but light green and alage forms every day. Since I did add the metal out stuff, I know I am not suppose to shock for 7 days, which is now up today. I have vacuumed everyday and every day there is alage to vacuum. Today the water is clear and light green, but kinda has a brown dingy tint to it also and what I vacuumed this evening appeared greenish brown. So do I treat for alage or metals...do I start to shock today and keep it there until it clears or what do you suggest?
21,000 gallons inground vinyl liner
sand filter
FC is 2.5 this evening, it has rained continual today
CC: 0
PH 7.8
TA: 90
CYA: 30

Test for metals first. If you don't have then you're merely fighting algae. And if it's algae, you won't clear it up unless you keep your FC at 12 or more.