Lime green pool and other levels are normal

I opened the pool cover last week (8 days today) and started testing and treating the pool. My levels seem to be normal now but there is still a lime green color to the pool. No algae seems to be present (to slime on walls). Here are my stats:

Above ground pool - 5,000 gal (Intex)
Water results: Chlorine 6 ppm
PH 7.4
TA 50 ppm

I normally wouldn't test for TA until I read a post here that sounded like the problem I'm facing but I didn't see any more responses from the OP. Any idea on what I can do?