New to this pool stuff, cloudy pool can't fix??

[Francie]

Ok, I bought a home with a 27' pool, about 20,000 gallons of water. The pool was completely green and we have gone from that to blue/cloudy now. I can't seem to get rid of the cloudy. Here are my stats:

ALK - 60
PH: 7.6
Free CL : 0.5
HRD: 100
CYA: 20

I have also used that first aid pool stuff and it is still cloudy. What should I do to get rid of this dead algae?? I can't see the bottom of pool. Thanks so much.
Francie Holder