Welcome!
If you've been following pool store methods, you've been feeding your pool pucks to chlorinate. They're handy, no doubt, but pucks don't just add chlorine, they add Cyanuric Acid as well. To kill bacteria and algae, you need to maintain a certain ratio of chlorine to CYA. The problem is that the chlorine dissipates but the CYA does not. It just keeps building. Two of the three most popular "shock" powders also contain CYA.
So what happens is you add some pucks or some shock and both CYA and Free Chlorine go up. Then the FC goes away. So you add more pucks. But the FC/CYA ratio is no longer correct. The FC is now all bound up to the CYA and can't do its job. So you add more pucks and powders. It's just an endless downward spiral. Each time you raise the chlorine level, you're putting the target a little further out of reach.
At some point the pool turns green or cloudy and the pool store sells you more CYA-laden products to drive the target FC level further out of reach. And after they've emptied your wallet, they pronounce your pool is suffering from "Chlorine Lock" or high Total Dissolved Solids and the cure is to drain the pool, refill, and get back on the merry-go-round.
The pool didn't go green in three days, so it won't get clear in three days, either. Sorry. To fix it right requires a proper test kit to begin with. Knowing exactly where your pool numbers are lets you make an informed decision whether or not any water needs replacing first, and then to monitor the FC levels while you
SLAM Process the pool. It's like a pool store "shock" but it's not a one-time megadose. It's a carefully regulated high amount of chlorine sustained for many days so it can actually kill the algae completely, and not just beat it down so it can return in a week.
Check out some of
these threads. Look at the pictures. Just do what they did.