Keep it simple. If you have algae already, a chlorine level of 4 isn't going to help. That's why nothing is happening. You need to shock your pool up to 12-15ppm (since we don't know your CYA/stabilizer level) and keep it there until the water clears. You cannot let it drop, you have to test it 2 to 3 times a day, and add bleach as needed to get it up there. You may have a clear pool in 2 days, or 2 weeks, depending on how infested it is, and how diligent YOU are.

Once you have spent several days killing anything and everything with lots and lots of chlorine, you can start wondering if you have metals as well. IF you still have a problem. Since you clearly have algae, you want to kill that NOW! Solve that first.