Do it early. With the temps now getting to 70's and 80's, it does not take long for the algae to start growing. Getting the pool circulating with proper disinfectant levels is key to keeping the pool in top shape. Some decide to wait until May to open their pools. If this is your choice, and you have a loop loc cover, we suggest starting the pump and filter without taking the cover off. We call this a jump start and this allows for a clear pool when you pull the cover off later.