When taking care of a pool we initially spend a significant amount of money on chemicals to place inside the pool and destroy any harmful bacteria in the water during the winter time. Sunshine is what cause the green color/bacteria in your pool. Algae grows in sunshine. The most cost efficient way to clean the pool after winter begins with purchasing or renting a 200 horsepower pump to suck the water completely out of the pool. The next step involves renting a pressure washer to clean off the walls on the inside of the pool. Next get a small plastic snow shovel to clean out the rest of the algae/bacteria left in the bottom of the pool after using the pressure washer. Finally make sure you have a water hose and a source of water then simply turn the hose on and fill up your pool.