If you pulled your pumps in the fall, you will want to clean out the skimmer and either clean or replace the filter pads and leaf basket before reinstalling the pumps. I personally leave my pumps running throughout the winter, and pull the pumps in the spring and clean them. It is best to start the pumps in the morning on a day that you are home all day to monitor the water level to be sure there are no leaks. The last thing you want is to burn a pump up because it ran dry.
Usually spring time brings a lot of rain and many ponds get a lot of runoff that clouds or muddies the water. This can result in a sludge build up that can cause problems with hair algae all summer. In this case you may want to consider installing a pressure filter. These filters do a great job of mechanically cleaning the water and have a back wash feature for self cleaning.
Don’t get discouraged by hair algae in the spring, this is a normal cycle. If you have a good bed of gravel in the bottom the algae will go away as the plants grow and the water temperature warms up. Don’t run out and get a UV clarifier to get rid of hair algae because it will have no affect. UV clarifiers only kill free floating algae that gives the water a pea soup look. I would not recommend algaecides either. Plants like water hyacinths, marsh betony, and watercress make very good water filters and grow quickly. Make sure you wait until the last frost to plant the water hyacinths.