We just moved to a home with an in ground pool. Previous owner said big storm came through last fall and dumped leaves, etc. they tarped it after that. We pulled the tarp last week and it was Black water and stunk. Got the sand filter opened and running. Pool store said to shock it a lot which we have. I have 12 gallons of shock in it now. We changed from Black, Dark green, light green. Now has a foam across the pool. I have the filter running, have scooped a lot of algae off the bottom. We can't afford to drain and refill and we have a well with high iron, so trying to fix what we have. Do we keep shocking it? Filter, backwash, keep skimming off the top?