High pH and green algae

I recently purchased a house with an in-ground pool. It turned green as soon as the weather warmed up and I have not been able to de-green it successfully. Though I can kill the algae with two gallons of chlorine bleach, I am not successful at removing the dead algae and it always comes back. The pool continues to have a high pH (>8) and low alkalinity (<40). I have a sand filter and the pool is a Foxx pool with a vinyl liner. Though there are no trees over the pool it is very hard to keep leaves, pine needles, bugs and grass out of the pool (it is on a hill and the wind blows everything in) and I wonder if that adds to the problem? Any suggestions will be appreciated.