We have a major algae problem with our pool here in Oklahoma!! In the spring we had black algae and now we have green algae. In the last week we have spen $$$ on liquid shock. One night we put 8 gallons in and it seemed to partially work then two nights later we added 4 more gallons. Our pool continues to get worse. My husband has also cleaned the sand (but not changed it), what else can we do? Our pool is 9 years old and we have never had algae this bad. Help!