Just bought a home with a pool, so I'm all new to this. Previous owner worked hard to get the water ready. We had it looking great and well balanced for 2 weeks, then had a rain. Pool turned green in a few hours. Tried an algaecide, followed by heavy shocking for 2 days. So far there's been no change. Pool store tested for metal, but they say there's no metal. Shocking heavy again for 3 more days. How long should it take before I see results? Should I be concerned or simply follow the course patiently?